diff --git a/Cargo.lock b/Cargo.lock
index 05bb5e0e5..7f00a2807 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -684,7 +684,7 @@ dependencies = [
 
 [[package]]
 name = "beacon_node"
-version = "4.2.0"
+version = "4.3.0"
 dependencies = [
  "beacon_chain",
  "clap",
@@ -891,7 +891,7 @@ dependencies = [
 
 [[package]]
 name = "boot_node"
-version = "4.2.0"
+version = "4.3.0"
 dependencies = [
  "beacon_node",
  "clap",
@@ -4165,7 +4165,7 @@ checksum = "830d08ce1d1d941e6b30645f1a0eb5643013d835ce3779a5fc208261dbe10f55"
 
 [[package]]
 name = "lcli"
-version = "4.2.0"
+version = "4.3.0"
 dependencies = [
  "account_utils",
  "beacon_chain",
@@ -4812,7 +4812,7 @@ dependencies = [
 
 [[package]]
 name = "lighthouse"
-version = "4.2.0"
+version = "4.3.0"
 dependencies = [
  "account_manager",
  "account_utils",
@@ -9108,6 +9108,7 @@ dependencies = [
  "smallvec",
  "ssz_types",
  "state_processing",
+ "strum",
  "superstruct 0.6.0",
  "swap_or_not_shuffle",
  "tempfile",
diff --git a/beacon_node/Cargo.toml b/beacon_node/Cargo.toml
index d3f43fad7..bd578099a 100644
--- a/beacon_node/Cargo.toml
+++ b/beacon_node/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "beacon_node"
-version = "4.2.0"
+version = "4.3.0"
 authors = ["Paul Hauner <paul@paulhauner.com>", "Age Manning <Age@AgeManning.com"]
 edition = "2021"
 
diff --git a/beacon_node/beacon_chain/src/beacon_chain.rs b/beacon_node/beacon_chain/src/beacon_chain.rs
index 266d5385b..f08915eaf 100644
--- a/beacon_node/beacon_chain/src/beacon_chain.rs
+++ b/beacon_node/beacon_chain/src/beacon_chain.rs
@@ -2664,6 +2664,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                         signature_verified_block.block_root(),
                         signature_verified_block,
                         notify_execution_layer,
+                        || Ok(()),
                     )
                     .await
                 {
@@ -2783,6 +2784,7 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         block_root: Hash256,
         unverified_block: B,
         notify_execution_layer: NotifyExecutionLayer,
+                publish_fn: impl FnOnce() -> Result<(), BlockError<T::EthSpec>> + Send + 'static,
     ) -> Result<AvailabilityProcessingStatus, BlockError<T::EthSpec>> {
         // Start the Prometheus timer.
         let _full_timer = metrics::start_timer(&metrics::BLOCK_PROCESSING_TIMES);
@@ -2798,6 +2800,9 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
             notify_execution_layer,
         )?;
 
+        //TODO(sean) error handling?
+            publish_fn()?;
+
         let executed_block = self
             .clone()
             .into_executed_block(execution_pending)
@@ -3073,7 +3078,9 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                     block_delay,
                     &state,
                     payload_verification_status,
+                    self.config.progressive_balances_mode,
                     &self.spec,
+                    &self.log,
                 )
                 .map_err(|e| BlockError::BeaconChainError(e.into()))?;
         }
@@ -6012,13 +6019,9 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
     /// Since we are likely calling this during the slot we are going to propose in, don't take into
     /// account the current slot when accounting for skips.
     pub fn is_healthy(&self, parent_root: &Hash256) -> Result<ChainHealth, Error> {
+        let cached_head = self.canonical_head.cached_head();
         // Check if the merge has been finalized.
-        if let Some(finalized_hash) = self
-            .canonical_head
-            .cached_head()
-            .forkchoice_update_parameters()
-            .finalized_hash
-        {
+        if let Some(finalized_hash) = cached_head.forkchoice_update_parameters().finalized_hash {
             if ExecutionBlockHash::zero() == finalized_hash {
                 return Ok(ChainHealth::PreMerge);
             }
@@ -6045,17 +6048,13 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
 
         // Check slots at the head of the chain.
         let prev_slot = current_slot.saturating_sub(Slot::new(1));
-        let head_skips = prev_slot.saturating_sub(self.canonical_head.cached_head().head_slot());
+        let head_skips = prev_slot.saturating_sub(cached_head.head_slot());
         let head_skips_check = head_skips.as_usize() <= self.config.builder_fallback_skips;
 
         // Check if finalization is advancing.
         let current_epoch = current_slot.epoch(T::EthSpec::slots_per_epoch());
-        let epochs_since_finalization = current_epoch.saturating_sub(
-            self.canonical_head
-                .cached_head()
-                .finalized_checkpoint()
-                .epoch,
-        );
+        let epochs_since_finalization =
+            current_epoch.saturating_sub(cached_head.finalized_checkpoint().epoch);
         let finalization_check = epochs_since_finalization.as_usize()
             <= self.config.builder_fallback_epochs_since_finalization;
 
diff --git a/beacon_node/beacon_chain/src/block_verification.rs b/beacon_node/beacon_chain/src/block_verification.rs
index 21fe10431..0f8f03e5f 100644
--- a/beacon_node/beacon_chain/src/block_verification.rs
+++ b/beacon_node/beacon_chain/src/block_verification.rs
@@ -57,6 +57,7 @@ use crate::execution_payload::{
     is_optimistic_candidate_block, validate_execution_payload_for_gossip, validate_merge_block,
     AllowOptimisticImport, NotifyExecutionLayer, PayloadNotifier,
 };
+use crate::observed_block_producers::SeenBlock;
 use crate::snapshot_cache::PreProcessingSnapshot;
 use crate::validator_monitor::HISTORIC_EPOCHS as VALIDATOR_MONITOR_HISTORIC_EPOCHS;
 use crate::validator_pubkey_cache::ValidatorPubkeyCache;
@@ -189,13 +190,6 @@ pub enum BlockError<T: EthSpec> {
     ///
     /// The block is valid and we have already imported a block with this hash.
     BlockIsAlreadyKnown,
-    /// A block for this proposer and slot has already been observed.
-    ///
-    /// ## Peer scoring
-    ///
-    /// The `proposer` has already proposed a block at this slot. The existing block may or may not
-    /// be equal to the given block.
-    RepeatProposal { proposer: u64, slot: Slot },
     /// The block slot exceeds the MAXIMUM_BLOCK_SLOT_NUMBER.
     ///
     /// ## Peer scoring
@@ -291,6 +285,14 @@ pub enum BlockError<T: EthSpec> {
     /// problems to worry about than losing peers, and we're doing the network a favour by
     /// disconnecting.
     ParentExecutionPayloadInvalid { parent_root: Hash256 },
+    /// The block is a slashable equivocation from the proposer.
+    ///
+    /// ## Peer scoring
+    ///
+    /// Honest peers shouldn't forward more than 1 equivocating block from the same proposer, so
+    /// we penalise them with a mid-tolerance error.
+    Slashable,
+    //TODO(sean) peer scoring docs
     /// A blob alone failed validation.
     BlobValidation(BlobError<T>),
     /// The block and blob together failed validation.
@@ -892,19 +894,6 @@ impl<T: BeaconChainTypes> GossipVerifiedBlock<T> {
             return Err(BlockError::BlockIsAlreadyKnown);
         }
 
-        // Check that we have not already received a block with a valid signature for this slot.
-        if chain
-            .observed_block_producers
-            .read()
-            .proposer_has_been_observed(block.message())
-            .map_err(|e| BlockError::BeaconChainError(e.into()))?
-        {
-            return Err(BlockError::RepeatProposal {
-                proposer: block.message().proposer_index(),
-                slot: block.slot(),
-            });
-        }
-
         // Do not process a block that doesn't descend from the finalized root.
         //
         // We check this *before* we load the parent so that we can return a more detailed error.
@@ -1020,17 +1009,16 @@ impl<T: BeaconChainTypes> GossipVerifiedBlock<T> {
         //
         // It's important to double-check that the proposer still hasn't been observed so we don't
         // have a race-condition when verifying two blocks simultaneously.
-        if chain
+        match chain
             .observed_block_producers
             .write()
-            .observe_proposer(block.message())
+            .observe_proposal(block_root, block.message())
             .map_err(|e| BlockError::BeaconChainError(e.into()))?
         {
-            return Err(BlockError::RepeatProposal {
-                proposer: block.message().proposer_index(),
-                slot: block.slot(),
-            });
-        }
+            SeenBlock::Slashable => return Err(BlockError::Slashable),
+            SeenBlock::Duplicate => return Err(BlockError::BlockIsAlreadyKnown),
+            SeenBlock::UniqueNonSlashable => {}
+        };
 
         if block.message().proposer_index() != expected_proposer as u64 {
             return Err(BlockError::IncorrectBlockProposer {
@@ -1293,6 +1281,12 @@ impl<T: BeaconChainTypes> ExecutionPendingBlock<T> {
         chain: &Arc<BeaconChain<T>>,
         notify_execution_layer: NotifyExecutionLayer,
     ) -> Result<Self, BlockError<T::EthSpec>> {
+        chain
+            .observed_block_producers
+            .write()
+            .observe_proposal(block_root, block.message())
+            .map_err(|e| BlockError::BeaconChainError(e.into()))?;
+
         if let Some(parent) = chain
             .canonical_head
             .fork_choice_read_lock()
diff --git a/beacon_node/beacon_chain/src/builder.rs b/beacon_node/beacon_chain/src/builder.rs
index 23f7692af..55fc24fea 100644
--- a/beacon_node/beacon_chain/src/builder.rs
+++ b/beacon_node/beacon_chain/src/builder.rs
@@ -343,7 +343,7 @@ where
         let beacon_block = genesis_block(&mut beacon_state, &self.spec)?;
 
         beacon_state
-            .build_all_caches(&self.spec)
+            .build_caches(&self.spec)
             .map_err(|e| format!("Failed to build genesis state caches: {:?}", e))?;
 
         let beacon_state_root = beacon_block.message().state_root();
@@ -433,7 +433,7 @@ where
         // Prime all caches before storing the state in the database and computing the tree hash
         // root.
         weak_subj_state
-            .build_all_caches(&self.spec)
+            .build_caches(&self.spec)
             .map_err(|e| format!("Error building caches on checkpoint state: {e:?}"))?;
         weak_subj_state
             .update_tree_hash_cache()
@@ -701,6 +701,8 @@ where
                 store.clone(),
                 Some(current_slot),
                 &self.spec,
+                self.chain_config.progressive_balances_mode,
+                &log,
             )?;
         }
 
@@ -714,7 +716,7 @@ where
 
         head_snapshot
             .beacon_state
-            .build_all_caches(&self.spec)
+            .build_caches(&self.spec)
             .map_err(|e| format!("Failed to build state caches: {:?}", e))?;
 
         // Perform a check to ensure that the finalization points of the head and fork choice are
@@ -840,9 +842,7 @@ where
             observed_sync_aggregators: <_>::default(),
             // TODO: allow for persisting and loading the pool from disk.
             observed_block_producers: <_>::default(),
-            // TODO: allow for persisting and loading the pool from disk.
             observed_blob_sidecars: <_>::default(),
-            // TODO: allow for persisting and loading the pool from disk.
             observed_voluntary_exits: <_>::default(),
             observed_proposer_slashings: <_>::default(),
             observed_attester_slashings: <_>::default(),
diff --git a/beacon_node/beacon_chain/src/chain_config.rs b/beacon_node/beacon_chain/src/chain_config.rs
index 34a5c9a4e..cc7a957ec 100644
--- a/beacon_node/beacon_chain/src/chain_config.rs
+++ b/beacon_node/beacon_chain/src/chain_config.rs
@@ -1,7 +1,7 @@
 pub use proto_array::{DisallowedReOrgOffsets, ReOrgThreshold};
 use serde_derive::{Deserialize, Serialize};
 use std::time::Duration;
-use types::{Checkpoint, Epoch};
+use types::{Checkpoint, Epoch, ProgressiveBalancesMode};
 
 pub const DEFAULT_RE_ORG_THRESHOLD: ReOrgThreshold = ReOrgThreshold(20);
 pub const DEFAULT_RE_ORG_MAX_EPOCHS_SINCE_FINALIZATION: Epoch = Epoch::new(2);
@@ -81,6 +81,8 @@ pub struct ChainConfig {
     pub always_prepare_payload: bool,
     /// Whether backfill sync processing should be rate-limited.
     pub enable_backfill_rate_limiting: bool,
+    /// Whether to use `ProgressiveBalancesCache` in unrealized FFG progression calculation.
+    pub progressive_balances_mode: ProgressiveBalancesMode,
 }
 
 impl Default for ChainConfig {
@@ -111,6 +113,7 @@ impl Default for ChainConfig {
             genesis_backfill: false,
             always_prepare_payload: false,
             enable_backfill_rate_limiting: true,
+            progressive_balances_mode: ProgressiveBalancesMode::Checked,
         }
     }
 }
diff --git a/beacon_node/beacon_chain/src/errors.rs b/beacon_node/beacon_chain/src/errors.rs
index e4c4ff251..774fb8618 100644
--- a/beacon_node/beacon_chain/src/errors.rs
+++ b/beacon_node/beacon_chain/src/errors.rs
@@ -216,6 +216,7 @@ pub enum BeaconChainError {
     BlsToExecutionConflictsWithPool,
     InconsistentFork(InconsistentFork),
     ProposerHeadForkChoiceError(fork_choice::Error<proto_array::Error>),
+    UnableToPublish,
     AvailabilityCheckError(AvailabilityCheckError),
 }
 
diff --git a/beacon_node/beacon_chain/src/fork_revert.rs b/beacon_node/beacon_chain/src/fork_revert.rs
index 084ae95e0..dc0e34277 100644
--- a/beacon_node/beacon_chain/src/fork_revert.rs
+++ b/beacon_node/beacon_chain/src/fork_revert.rs
@@ -10,7 +10,10 @@ use state_processing::{
 use std::sync::Arc;
 use std::time::Duration;
 use store::{iter::ParentRootBlockIterator, HotColdDB, ItemStore};
-use types::{BeaconState, ChainSpec, EthSpec, ForkName, Hash256, SignedBeaconBlock, Slot};
+use types::{
+    BeaconState, ChainSpec, EthSpec, ForkName, Hash256, ProgressiveBalancesMode, SignedBeaconBlock,
+    Slot,
+};
 
 const CORRUPT_DB_MESSAGE: &str = "The database could be corrupt. Check its file permissions or \
                                   consider deleting it by running with the --purge-db flag.";
@@ -100,6 +103,8 @@ pub fn reset_fork_choice_to_finalization<E: EthSpec, Hot: ItemStore<E>, Cold: It
     store: Arc<HotColdDB<E, Hot, Cold>>,
     current_slot: Option<Slot>,
     spec: &ChainSpec,
+    progressive_balances_mode: ProgressiveBalancesMode,
+    log: &Logger,
 ) -> Result<ForkChoice<BeaconForkChoiceStore<E, Hot, Cold>, E>, String> {
     // Fetch finalized block.
     let finalized_checkpoint = head_state.finalized_checkpoint();
@@ -197,7 +202,9 @@ pub fn reset_fork_choice_to_finalization<E: EthSpec, Hot: ItemStore<E>, Cold: It
                 Duration::from_secs(0),
                 &state,
                 payload_verification_status,
+                progressive_balances_mode,
                 spec,
+                log,
             )
             .map_err(|e| format!("Error applying replayed block to fork choice: {:?}", e))?;
     }
diff --git a/beacon_node/beacon_chain/src/observed_block_producers.rs b/beacon_node/beacon_chain/src/observed_block_producers.rs
index b5995121b..f76fc5379 100644
--- a/beacon_node/beacon_chain/src/observed_block_producers.rs
+++ b/beacon_node/beacon_chain/src/observed_block_producers.rs
@@ -1,9 +1,10 @@
 //! Provides the `ObservedBlockProducers` struct which allows for rejecting gossip blocks from
 //! validators that have already produced a block.
 
+use std::collections::hash_map::Entry;
 use std::collections::{HashMap, HashSet};
 use std::marker::PhantomData;
-use types::{BeaconBlockRef, Epoch, EthSpec, Slot, Unsigned};
+use types::{BeaconBlockRef, Epoch, EthSpec, Hash256, Slot, Unsigned};
 
 #[derive(Debug, PartialEq)]
 pub enum Error {
@@ -14,6 +15,12 @@ pub enum Error {
     ValidatorIndexTooHigh(u64),
 }
 
+#[derive(Eq, Hash, PartialEq, Debug, Default)]
+struct ProposalKey {
+    slot: Slot,
+    proposer: u64,
+}
+
 /// Maintains a cache of observed `(block.slot, block.proposer)`.
 ///
 /// The cache supports pruning based upon the finalized epoch. It does not automatically prune, you
@@ -27,7 +34,7 @@ pub enum Error {
 /// known_distinct_shufflings` which is much smaller.
 pub struct ObservedBlockProducers<E: EthSpec> {
     finalized_slot: Slot,
-    items: HashMap<Slot, HashSet<u64>>,
+    items: HashMap<ProposalKey, HashSet<Hash256>>,
     _phantom: PhantomData<E>,
 }
 
@@ -42,6 +49,24 @@ impl<E: EthSpec> Default for ObservedBlockProducers<E> {
     }
 }
 
+pub enum SeenBlock {
+    Duplicate,
+    Slashable,
+    UniqueNonSlashable,
+}
+
+impl SeenBlock {
+    pub fn proposer_previously_observed(self) -> bool {
+        match self {
+            Self::Duplicate | Self::Slashable => true,
+            Self::UniqueNonSlashable => false,
+        }
+    }
+    pub fn is_slashable(&self) -> bool {
+        matches!(self, Self::Slashable)
+    }
+}
+
 impl<E: EthSpec> ObservedBlockProducers<E> {
     /// Observe that the `block` was produced by `block.proposer_index` at `block.slot`. This will
     /// update `self` so future calls to it indicate that this block is known.
@@ -52,16 +77,44 @@ impl<E: EthSpec> ObservedBlockProducers<E> {
     ///
     /// - `block.proposer_index` is greater than `VALIDATOR_REGISTRY_LIMIT`.
     /// - `block.slot` is equal to or less than the latest pruned `finalized_slot`.
-    pub fn observe_proposer(&mut self, block: BeaconBlockRef<'_, E>) -> Result<bool, Error> {
+    pub fn observe_proposal(
+        &mut self,
+        block_root: Hash256,
+        block: BeaconBlockRef<'_, E>,
+    ) -> Result<SeenBlock, Error> {
         self.sanitize_block(block)?;
 
-        let did_not_exist = self
-            .items
-            .entry(block.slot())
-            .or_insert_with(|| HashSet::with_capacity(E::SlotsPerEpoch::to_usize()))
-            .insert(block.proposer_index());
+        let key = ProposalKey {
+            slot: block.slot(),
+            proposer: block.proposer_index(),
+        };
 
-        Ok(!did_not_exist)
+        let entry = self.items.entry(key);
+
+        let slashable_proposal = match entry {
+            Entry::Occupied(mut occupied_entry) => {
+                let block_roots = occupied_entry.get_mut();
+                let newly_inserted = block_roots.insert(block_root);
+
+                let is_equivocation = block_roots.len() > 1;
+
+                if is_equivocation {
+                    SeenBlock::Slashable
+                } else if !newly_inserted {
+                    SeenBlock::Duplicate
+                } else {
+                    SeenBlock::UniqueNonSlashable
+                }
+            }
+            Entry::Vacant(vacant_entry) => {
+                let block_roots = HashSet::from([block_root]);
+                vacant_entry.insert(block_roots);
+
+                SeenBlock::UniqueNonSlashable
+            }
+        };
+
+        Ok(slashable_proposal)
     }
 
     /// Returns `Ok(true)` if the `block` has been observed before, `Ok(false)` if not. Does not
@@ -72,15 +125,33 @@ impl<E: EthSpec> ObservedBlockProducers<E> {
     ///
     /// - `block.proposer_index` is greater than `VALIDATOR_REGISTRY_LIMIT`.
     /// - `block.slot` is equal to or less than the latest pruned `finalized_slot`.
-    pub fn proposer_has_been_observed(&self, block: BeaconBlockRef<'_, E>) -> Result<bool, Error> {
+    pub fn proposer_has_been_observed(
+        &self,
+        block: BeaconBlockRef<'_, E>,
+        block_root: Hash256,
+    ) -> Result<SeenBlock, Error> {
         self.sanitize_block(block)?;
 
-        let exists = self
-            .items
-            .get(&block.slot())
-            .map_or(false, |set| set.contains(&block.proposer_index()));
+        let key = ProposalKey {
+            slot: block.slot(),
+            proposer: block.proposer_index(),
+        };
 
-        Ok(exists)
+        if let Some(block_roots) = self.items.get(&key) {
+            let block_already_known = block_roots.contains(&block_root);
+            let no_prev_known_blocks =
+                block_roots.difference(&HashSet::from([block_root])).count() == 0;
+
+            if !no_prev_known_blocks {
+                Ok(SeenBlock::Slashable)
+            } else if block_already_known {
+                Ok(SeenBlock::Duplicate)
+            } else {
+                Ok(SeenBlock::UniqueNonSlashable)
+            }
+        } else {
+            Ok(SeenBlock::UniqueNonSlashable)
+        }
     }
 
     /// Returns `Ok(())` if the given `block` is sane.
@@ -112,15 +183,15 @@ impl<E: EthSpec> ObservedBlockProducers<E> {
         }
 
         self.finalized_slot = finalized_slot;
-        self.items.retain(|slot, _set| *slot > finalized_slot);
+        self.items.retain(|key, _| key.slot > finalized_slot);
     }
 
     /// Returns `true` if the given `validator_index` has been stored in `self` at `epoch`.
     ///
     /// This is useful for doppelganger detection.
     pub fn index_seen_at_epoch(&self, validator_index: u64, epoch: Epoch) -> bool {
-        self.items.iter().any(|(slot, producers)| {
-            slot.epoch(E::slots_per_epoch()) == epoch && producers.contains(&validator_index)
+        self.items.iter().any(|(key, _)| {
+            key.slot.epoch(E::slots_per_epoch()) == epoch && key.proposer == validator_index
         })
     }
 }
@@ -148,9 +219,12 @@ mod tests {
 
         // Slot 0, proposer 0
         let block_a = get_block(0, 0);
+        let block_root = block_a.canonical_root();
 
         assert_eq!(
-            cache.observe_proposer(block_a.to_ref()),
+            cache
+                .observe_proposal(block_root, block_a.to_ref())
+                .map(SeenBlock::proposer_previously_observed),
             Ok(false),
             "can observe proposer, indicates proposer unobserved"
         );
@@ -164,7 +238,10 @@ mod tests {
         assert_eq!(
             cache
                 .items
-                .get(&Slot::new(0))
+                .get(&ProposalKey {
+                    slot: Slot::new(0),
+                    proposer: 0
+                })
                 .expect("slot zero should be present")
                 .len(),
             1,
@@ -182,7 +259,10 @@ mod tests {
         assert_eq!(
             cache
                 .items
-                .get(&Slot::new(0))
+                .get(&ProposalKey {
+                    slot: Slot::new(0),
+                    proposer: 0
+                })
                 .expect("slot zero should be present")
                 .len(),
             1,
@@ -207,9 +287,12 @@ mod tests {
 
         // First slot of finalized epoch, proposer 0
         let block_b = get_block(E::slots_per_epoch(), 0);
+        let block_root_b = block_b.canonical_root();
 
         assert_eq!(
-            cache.observe_proposer(block_b.to_ref()),
+            cache
+                .observe_proposal(block_root_b, block_b.to_ref())
+                .map(SeenBlock::proposer_previously_observed),
             Err(Error::FinalizedBlock {
                 slot: E::slots_per_epoch().into(),
                 finalized_slot: E::slots_per_epoch().into(),
@@ -229,7 +312,9 @@ mod tests {
         let block_b = get_block(three_epochs, 0);
 
         assert_eq!(
-            cache.observe_proposer(block_b.to_ref()),
+            cache
+                .observe_proposal(block_root_b, block_b.to_ref())
+                .map(SeenBlock::proposer_previously_observed),
             Ok(false),
             "can insert non-finalized block"
         );
@@ -238,7 +323,10 @@ mod tests {
         assert_eq!(
             cache
                 .items
-                .get(&Slot::new(three_epochs))
+                .get(&ProposalKey {
+                    slot: Slot::new(three_epochs),
+                    proposer: 0
+                })
                 .expect("the three epochs slot should be present")
                 .len(),
             1,
@@ -262,7 +350,10 @@ mod tests {
         assert_eq!(
             cache
                 .items
-                .get(&Slot::new(three_epochs))
+                .get(&ProposalKey {
+                    slot: Slot::new(three_epochs),
+                    proposer: 0
+                })
                 .expect("the three epochs slot should be present")
                 .len(),
             1,
@@ -276,24 +367,33 @@ mod tests {
 
         // Slot 0, proposer 0
         let block_a = get_block(0, 0);
+        let block_root_a = block_a.canonical_root();
 
         assert_eq!(
-            cache.proposer_has_been_observed(block_a.to_ref()),
+            cache
+                .proposer_has_been_observed(block_a.to_ref(), block_a.canonical_root())
+                .map(|x| x.proposer_previously_observed()),
             Ok(false),
             "no observation in empty cache"
         );
         assert_eq!(
-            cache.observe_proposer(block_a.to_ref()),
+            cache
+                .observe_proposal(block_root_a, block_a.to_ref())
+                .map(SeenBlock::proposer_previously_observed),
             Ok(false),
             "can observe proposer, indicates proposer unobserved"
         );
         assert_eq!(
-            cache.proposer_has_been_observed(block_a.to_ref()),
+            cache
+                .proposer_has_been_observed(block_a.to_ref(), block_a.canonical_root())
+                .map(|x| x.proposer_previously_observed()),
             Ok(true),
             "observed block is indicated as true"
         );
         assert_eq!(
-            cache.observe_proposer(block_a.to_ref()),
+            cache
+                .observe_proposal(block_root_a, block_a.to_ref())
+                .map(SeenBlock::proposer_previously_observed),
             Ok(true),
             "observing again indicates true"
         );
@@ -303,7 +403,10 @@ mod tests {
         assert_eq!(
             cache
                 .items
-                .get(&Slot::new(0))
+                .get(&ProposalKey {
+                    slot: Slot::new(0),
+                    proposer: 0
+                })
                 .expect("slot zero should be present")
                 .len(),
             1,
@@ -312,24 +415,33 @@ mod tests {
 
         // Slot 1, proposer 0
         let block_b = get_block(1, 0);
+        let block_root_b = block_b.canonical_root();
 
         assert_eq!(
-            cache.proposer_has_been_observed(block_b.to_ref()),
+            cache
+                .proposer_has_been_observed(block_b.to_ref(), block_b.canonical_root())
+                .map(|x| x.proposer_previously_observed()),
             Ok(false),
             "no observation for new slot"
         );
         assert_eq!(
-            cache.observe_proposer(block_b.to_ref()),
+            cache
+                .observe_proposal(block_root_b, block_b.to_ref())
+                .map(SeenBlock::proposer_previously_observed),
             Ok(false),
             "can observe proposer for new slot, indicates proposer unobserved"
         );
         assert_eq!(
-            cache.proposer_has_been_observed(block_b.to_ref()),
+            cache
+                .proposer_has_been_observed(block_b.to_ref(), block_b.canonical_root())
+                .map(|x| x.proposer_previously_observed()),
             Ok(true),
             "observed block in slot 1 is indicated as true"
         );
         assert_eq!(
-            cache.observe_proposer(block_b.to_ref()),
+            cache
+                .observe_proposal(block_root_b, block_b.to_ref())
+                .map(SeenBlock::proposer_previously_observed),
             Ok(true),
             "observing slot 1 again indicates true"
         );
@@ -339,7 +451,10 @@ mod tests {
         assert_eq!(
             cache
                 .items
-                .get(&Slot::new(0))
+                .get(&ProposalKey {
+                    slot: Slot::new(0),
+                    proposer: 0
+                })
                 .expect("slot zero should be present")
                 .len(),
             1,
@@ -348,7 +463,10 @@ mod tests {
         assert_eq!(
             cache
                 .items
-                .get(&Slot::new(1))
+                .get(&ProposalKey {
+                    slot: Slot::new(1),
+                    proposer: 0
+                })
                 .expect("slot zero should be present")
                 .len(),
             1,
@@ -357,45 +475,54 @@ mod tests {
 
         // Slot 0, proposer 1
         let block_c = get_block(0, 1);
+        let block_root_c = block_c.canonical_root();
 
         assert_eq!(
-            cache.proposer_has_been_observed(block_c.to_ref()),
+            cache
+                .proposer_has_been_observed(block_c.to_ref(), block_c.canonical_root())
+                .map(|x| x.proposer_previously_observed()),
             Ok(false),
             "no observation for new proposer"
         );
         assert_eq!(
-            cache.observe_proposer(block_c.to_ref()),
+            cache
+                .observe_proposal(block_root_c, block_c.to_ref())
+                .map(SeenBlock::proposer_previously_observed),
             Ok(false),
             "can observe new proposer, indicates proposer unobserved"
         );
         assert_eq!(
-            cache.proposer_has_been_observed(block_c.to_ref()),
+            cache
+                .proposer_has_been_observed(block_c.to_ref(), block_c.canonical_root())
+                .map(|x| x.proposer_previously_observed()),
             Ok(true),
             "observed new proposer block is indicated as true"
         );
         assert_eq!(
-            cache.observe_proposer(block_c.to_ref()),
+            cache
+                .observe_proposal(block_root_c, block_c.to_ref())
+                .map(SeenBlock::proposer_previously_observed),
             Ok(true),
             "observing new proposer again indicates true"
         );
 
         assert_eq!(cache.finalized_slot, 0, "finalized slot is zero");
-        assert_eq!(cache.items.len(), 2, "two slots should be present");
+        assert_eq!(cache.items.len(), 3, "three slots should be present");
         assert_eq!(
             cache
                 .items
-                .get(&Slot::new(0))
-                .expect("slot zero should be present")
-                .len(),
+                .iter()
+                .filter(|(k, _)| k.slot == cache.finalized_slot)
+                .count(),
             2,
             "two proposers should be present in slot 0"
         );
         assert_eq!(
             cache
                 .items
-                .get(&Slot::new(1))
-                .expect("slot zero should be present")
-                .len(),
+                .iter()
+                .filter(|(k, _)| k.slot == Slot::new(1))
+                .count(),
             1,
             "only one proposer should be present in slot 1"
         );
diff --git a/beacon_node/beacon_chain/src/test_utils.rs b/beacon_node/beacon_chain/src/test_utils.rs
index 32b5f2139..c34cab1e7 100644
--- a/beacon_node/beacon_chain/src/test_utils.rs
+++ b/beacon_node/beacon_chain/src/test_utils.rs
@@ -808,6 +808,15 @@ where
         state.get_block_root(slot).unwrap() == state.get_block_root(slot - 1).unwrap()
     }
 
+    pub async fn make_blinded_block(
+        &self,
+        state: BeaconState<E>,
+        slot: Slot,
+    ) -> (SignedBlindedBeaconBlock<E>, BeaconState<E>) {
+        let (unblinded, new_state) = self.make_block(state, slot).await;
+        (unblinded.into(), new_state)
+    }
+
     /// Returns a newly created block, signed by the proposer for the given slot.
     pub async fn make_block(
         &self,
@@ -820,9 +829,7 @@ where
         complete_state_advance(&mut state, None, slot, &self.spec)
             .expect("should be able to advance state to slot");
 
-        state
-            .build_all_caches(&self.spec)
-            .expect("should build caches");
+        state.build_caches(&self.spec).expect("should build caches");
 
         let proposer_index = state.get_beacon_proposer_index(slot, &self.spec).unwrap();
 
@@ -906,9 +913,7 @@ where
         complete_state_advance(&mut state, None, slot, &self.spec)
             .expect("should be able to advance state to slot");
 
-        state
-            .build_all_caches(&self.spec)
-            .expect("should build caches");
+        state.build_caches(&self.spec).expect("should build caches");
 
         let proposer_index = state.get_beacon_proposer_index(slot, &self.spec).unwrap();
 
@@ -1626,6 +1631,36 @@ where
         .sign(sk, &fork, genesis_validators_root, &self.chain.spec)
     }
 
+    pub fn add_proposer_slashing(&self, validator_index: u64) -> Result<(), String> {
+        let propposer_slashing = self.make_proposer_slashing(validator_index);
+        if let ObservationOutcome::New(verified_proposer_slashing) = self
+            .chain
+            .verify_proposer_slashing_for_gossip(propposer_slashing)
+            .expect("should verify proposer slashing for gossip")
+        {
+            self.chain
+                .import_proposer_slashing(verified_proposer_slashing);
+            Ok(())
+        } else {
+            Err("should observe new proposer slashing".to_string())
+        }
+    }
+
+    pub fn add_attester_slashing(&self, validator_indices: Vec<u64>) -> Result<(), String> {
+        let attester_slashing = self.make_attester_slashing(validator_indices);
+        if let ObservationOutcome::New(verified_attester_slashing) = self
+            .chain
+            .verify_attester_slashing_for_gossip(attester_slashing)
+            .expect("should verify attester slashing for gossip")
+        {
+            self.chain
+                .import_attester_slashing(verified_attester_slashing);
+            Ok(())
+        } else {
+            Err("should observe new attester slashing".to_string())
+        }
+    }
+
     pub fn add_bls_to_execution_change(
         &self,
         validator_index: u64,
@@ -1804,7 +1839,7 @@ where
         self.set_current_slot(slot);
         let block_hash: SignedBeaconBlockHash = self
             .chain
-            .process_block(block_root, block.into(), NotifyExecutionLayer::Yes)
+            .process_block(block_root, block.into(), NotifyExecutionLayer::Yes,|| Ok(()),)
             .await?
             .try_into()
             .unwrap();
@@ -1823,6 +1858,7 @@ where
                 wrapped_block.canonical_root(),
                 wrapped_block,
                 NotifyExecutionLayer::Yes,
+                || Ok(()),
             )
             .await?
             .try_into()
diff --git a/beacon_node/beacon_chain/tests/block_verification.rs b/beacon_node/beacon_chain/tests/block_verification.rs
index 5280fd518..48bd8f2dd 100644
--- a/beacon_node/beacon_chain/tests/block_verification.rs
+++ b/beacon_node/beacon_chain/tests/block_verification.rs
@@ -459,6 +459,7 @@ async fn assert_invalid_signature(
                 chain_segment_blobs[block_index].clone(),
             ),
             NotifyExecutionLayer::Yes,
+            || Ok(()),
         )
         .await;
     assert!(
@@ -526,6 +527,7 @@ async fn invalid_signature_gossip_block() {
                         signed_block.canonical_root(),
                         Arc::new(signed_block),
                         NotifyExecutionLayer::Yes,
+                        || Ok(()),
                     )
                     .await,
                 Err(BlockError::InvalidSignature)
@@ -859,6 +861,7 @@ async fn block_gossip_verification() {
                 gossip_verified.block_root,
                 gossip_verified,
                 NotifyExecutionLayer::Yes,
+                || Ok(()),
             )
             .await
             .expect("should import valid gossip verified block");
@@ -1069,11 +1072,7 @@ async fn block_gossip_verification() {
     assert!(
         matches!(
             unwrap_err(harness.chain.verify_block_for_gossip(Arc::new(block.clone()).into()).await),
-            BlockError::RepeatProposal {
-                proposer,
-                slot,
-            }
-            if proposer == other_proposer && slot == block.message().slot()
+            BlockError::BlockIsAlreadyKnown,
         ),
         "should register any valid signature against the proposer, even if the block failed later verification"
     );
@@ -1106,11 +1105,7 @@ async fn block_gossip_verification() {
                 .await
                 .err()
                 .expect("should error when processing known block"),
-            BlockError::RepeatProposal {
-                proposer,
-                slot,
-            }
-            if proposer == block.message().proposer_index() && slot == block.message().slot()
+            BlockError::BlockIsAlreadyKnown
         ),
         "the second proposal by this validator should be rejected"
     );
@@ -1159,6 +1154,7 @@ async fn verify_block_for_gossip_slashing_detection() {
             verified_block.block_root,
             verified_block,
             NotifyExecutionLayer::Yes,
+            || Ok(()),
         )
         .await
         .unwrap();
@@ -1198,6 +1194,7 @@ async fn verify_block_for_gossip_doppelganger_detection() {
             verified_block.block_root,
             verified_block,
             NotifyExecutionLayer::Yes,
+            || Ok(()),
         )
         .await
         .unwrap();
@@ -1345,6 +1342,7 @@ async fn add_base_block_to_altair_chain() {
                 base_block.canonical_root(),
                 Arc::new(base_block.clone()),
                 NotifyExecutionLayer::Yes,
+                || Ok(()),
             )
             .await
             .err()
@@ -1479,6 +1477,7 @@ async fn add_altair_block_to_base_chain() {
                 altair_block.canonical_root(),
                 Arc::new(altair_block.clone()),
                 NotifyExecutionLayer::Yes,
+                || Ok(()),
             )
             .await
             .err()
diff --git a/beacon_node/beacon_chain/tests/capella.rs b/beacon_node/beacon_chain/tests/capella.rs
index e910e8134..f0b799ec9 100644
--- a/beacon_node/beacon_chain/tests/capella.rs
+++ b/beacon_node/beacon_chain/tests/capella.rs
@@ -133,13 +133,8 @@ async fn base_altair_merge_capella() {
     for _ in (merge_fork_slot.as_u64() + 3)..capella_fork_slot.as_u64() {
         harness.extend_slots(1).await;
         let block = &harness.chain.head_snapshot().beacon_block;
-        let full_payload: FullPayload<E> = block
-            .message()
-            .body()
-            .execution_payload()
-            .unwrap()
-            .clone()
-            .into();
+        let full_payload: FullPayload<E> =
+            block.message().body().execution_payload().unwrap().into();
         // pre-capella shouldn't have withdrawals
         assert!(full_payload.withdrawals_root().is_err());
         execution_payloads.push(full_payload);
@@ -151,13 +146,8 @@ async fn base_altair_merge_capella() {
     for _ in 0..16 {
         harness.extend_slots(1).await;
         let block = &harness.chain.head_snapshot().beacon_block;
-        let full_payload: FullPayload<E> = block
-            .message()
-            .body()
-            .execution_payload()
-            .unwrap()
-            .clone()
-            .into();
+        let full_payload: FullPayload<E> =
+            block.message().body().execution_payload().unwrap().into();
         // post-capella should have withdrawals
         assert!(full_payload.withdrawals_root().is_ok());
         execution_payloads.push(full_payload);
diff --git a/beacon_node/beacon_chain/tests/payload_invalidation.rs b/beacon_node/beacon_chain/tests/payload_invalidation.rs
index 65860d204..60ba8f288 100644
--- a/beacon_node/beacon_chain/tests/payload_invalidation.rs
+++ b/beacon_node/beacon_chain/tests/payload_invalidation.rs
@@ -698,6 +698,7 @@ async fn invalidates_all_descendants() {
             fork_block.canonical_root(),
             Arc::new(fork_block),
             NotifyExecutionLayer::Yes,
+            || Ok(()),
         )
         .await
         .unwrap()
@@ -797,6 +798,7 @@ async fn switches_heads() {
             fork_block.canonical_root(),
             Arc::new(fork_block),
             NotifyExecutionLayer::Yes,
+            || Ok(()),
         )
         .await
         .unwrap()
@@ -1055,7 +1057,9 @@ async fn invalid_parent() {
 
     // Ensure the block built atop an invalid payload is invalid for import.
     assert!(matches!(
-        rig.harness.chain.process_block(block.canonical_root(), block.clone(),  NotifyExecutionLayer::Yes).await,
+        rig.harness.chain.process_block(block.canonical_root(), block.clone(), NotifyExecutionLayer::Yes,
+            || Ok(()),
+        ).await,
         Err(BlockError::ParentExecutionPayloadInvalid { parent_root: invalid_root })
         if invalid_root == parent_root
     ));
@@ -1069,8 +1073,9 @@ async fn invalid_parent() {
             Duration::from_secs(0),
             &state,
             PayloadVerificationStatus::Optimistic,
+            rig.harness.chain.config.progressive_balances_mode,
             &rig.harness.chain.spec,
-
+            rig.harness.logger()
         ),
         Err(ForkChoiceError::ProtoArrayStringError(message))
         if message.contains(&format!(
@@ -1341,7 +1346,12 @@ async fn build_optimistic_chain(
     for block in blocks {
         rig.harness
             .chain
-            .process_block(block.canonical_root(), block, NotifyExecutionLayer::Yes)
+            .process_block(
+                block.canonical_root(),
+                block,
+                NotifyExecutionLayer::Yes,
+                || Ok(()),
+            )
             .await
             .unwrap();
     }
@@ -1901,6 +1911,7 @@ async fn recover_from_invalid_head_by_importing_blocks() {
             fork_block.canonical_root(),
             fork_block.clone(),
             NotifyExecutionLayer::Yes,
+            || Ok(()),
         )
         .await
         .unwrap();
diff --git a/beacon_node/beacon_chain/tests/store_tests.rs b/beacon_node/beacon_chain/tests/store_tests.rs
index c58234b6e..7a86b5f93 100644
--- a/beacon_node/beacon_chain/tests/store_tests.rs
+++ b/beacon_node/beacon_chain/tests/store_tests.rs
@@ -2178,6 +2178,7 @@ async fn weak_subjectivity_sync() {
                 full_block.canonical_root(),
                 BlockWrapper::new(Arc::new(full_block), blobs),
                 NotifyExecutionLayer::Yes,
+                || Ok(()),
             )
             .await
             .unwrap();
diff --git a/beacon_node/beacon_chain/tests/tests.rs b/beacon_node/beacon_chain/tests/tests.rs
index 163930f39..80e4992ea 100644
--- a/beacon_node/beacon_chain/tests/tests.rs
+++ b/beacon_node/beacon_chain/tests/tests.rs
@@ -686,6 +686,7 @@ async fn run_skip_slot_test(skip_slots: u64) {
             harness_a.chain.head_snapshot().beacon_block_root,
             harness_a.get_head_block(),
             NotifyExecutionLayer::Yes,
+                            || Ok(())
         )
         .await
         .unwrap();
diff --git a/beacon_node/http_api/src/block_rewards.rs b/beacon_node/http_api/src/block_rewards.rs
index 828be8e57..299bc019c 100644
--- a/beacon_node/http_api/src/block_rewards.rs
+++ b/beacon_node/http_api/src/block_rewards.rs
@@ -49,7 +49,7 @@ pub fn get_block_rewards<T: BeaconChainTypes>(
         .map_err(beacon_chain_error)?;
 
     state
-        .build_all_caches(&chain.spec)
+        .build_caches(&chain.spec)
         .map_err(beacon_state_error)?;
 
     let mut reward_cache = Default::default();
diff --git a/beacon_node/http_api/src/lib.rs b/beacon_node/http_api/src/lib.rs
index 1a2a14611..c0d8a9615 100644
--- a/beacon_node/http_api/src/lib.rs
+++ b/beacon_node/http_api/src/lib.rs
@@ -32,7 +32,7 @@ use beacon_chain::{
 pub use block_id::BlockId;
 use directory::DEFAULT_ROOT_DIR;
 use eth2::types::{
-    self as api_types, EndpointVersion, ForkChoice, ForkChoiceNode, SignedBlockContents,
+    self as api_types, BroadcastValidation, EndpointVersion, ForkChoice, ForkChoiceNode, SignedBlockContents,
     SkipRandaoVerification, ValidatorId, ValidatorStatus,
 };
 use lighthouse_network::{types::SyncState, EnrExt, NetworkGlobals, PeerId, PubsubMessage};
@@ -41,7 +41,9 @@ use logging::SSELoggingComponents;
 use network::{NetworkMessage, NetworkSenders, ValidatorSubscriptionMessage};
 use operation_pool::ReceivedPreCapella;
 use parking_lot::RwLock;
-use publish_blocks::ProvenancedBlock;
+pub use publish_blocks::{
+    publish_blinded_block, publish_block, reconstruct_block, ProvenancedBlock,
+};
 use serde::{Deserialize, Serialize};
 use slog::{crit, debug, error, info, warn, Logger};
 use slot_clock::SlotClock;
@@ -325,6 +327,7 @@ pub fn serve<T: BeaconChainTypes>(
     };
 
     let eth_v1 = single_version(V1);
+    let eth_v2 = single_version(V2);
 
     // Create a `warp` filter that provides access to the network globals.
     let inner_network_globals = ctx.network_globals.clone();
@@ -1223,16 +1226,59 @@ pub fn serve<T: BeaconChainTypes>(
              log: Logger| async move {
                 publish_blocks::publish_block(
                     None,
-                    ProvenancedBlock::Local(block_contents),
+                    ProvenancedBlock::local(block_contents),
                     chain,
                     &network_tx,
                     log,
+                    BroadcastValidation::default(),
                 )
                 .await
                 .map(|()| warp::reply().into_response())
             },
         );
 
+    let post_beacon_blocks_v2 = eth_v2
+        .and(warp::path("beacon"))
+        .and(warp::path("blocks"))
+        .and(warp::query::<api_types::BroadcastValidationQuery>())
+        .and(warp::path::end())
+        .and(warp::body::json())
+        .and(chain_filter.clone())
+        .and(network_tx_filter.clone())
+        .and(log_filter.clone())
+        .then(
+            |validation_level: api_types::BroadcastValidationQuery,
+            block_contents: SignedBlockContents<T::EthSpec>,
+             chain: Arc<BeaconChain<T>>,
+             network_tx: UnboundedSender<NetworkMessage<T::EthSpec>>,
+             log: Logger| async move {
+                match publish_blocks::publish_block(
+                    None,
+                    ProvenancedBlock::local(block_contents),
+                    chain,
+                    &network_tx,
+                    log,
+                    validation_level.broadcast_validation,
+                )
+                .await
+                {
+                    Ok(()) => warp::reply().into_response(),
+                    Err(e) => match warp_utils::reject::handle_rejection(e).await {
+                        Ok(reply) => reply.into_response(),
+                        Err(_) => warp::reply::with_status(
+                            StatusCode::INTERNAL_SERVER_ERROR,
+                            eth2::StatusCode::INTERNAL_SERVER_ERROR,
+                        )
+                        .into_response(),
+                    },
+                }
+            },
+        );
+
+    /*
+     * beacon/blocks
+     */
+
     // POST beacon/blinded_blocks
     let post_beacon_blinded_blocks = eth_v1
         .and(warp::path("beacon"))
@@ -1247,9 +1293,52 @@ pub fn serve<T: BeaconChainTypes>(
              chain: Arc<BeaconChain<T>>,
              network_tx: UnboundedSender<NetworkMessage<T::EthSpec>>,
              log: Logger| async move {
-                publish_blocks::publish_blinded_block(block, chain, &network_tx, log)
-                    .await
-                    .map(|()| warp::reply().into_response())
+                publish_blocks::publish_blinded_block(
+                    block,
+                    chain,
+                    &network_tx,
+                    log,
+                    BroadcastValidation::default(),
+                )
+                .await
+                .map(|()| warp::reply().into_response())
+            },
+        );
+
+    let post_beacon_blinded_blocks_v2 = eth_v2
+        .and(warp::path("beacon"))
+        .and(warp::path("blinded_blocks"))
+        .and(warp::query::<api_types::BroadcastValidationQuery>())
+        .and(warp::path::end())
+        .and(warp::body::json())
+        .and(chain_filter.clone())
+        .and(network_tx_filter.clone())
+        .and(log_filter.clone())
+        .then(
+            |validation_level: api_types::BroadcastValidationQuery,
+             block_contents: SignedBlockContents<T::EthSpec, BlindedPayload<_>>,
+             chain: Arc<BeaconChain<T>>,
+             network_tx: UnboundedSender<NetworkMessage<T::EthSpec>>,
+             log: Logger| async move {
+                match publish_blocks::publish_blinded_block(
+                    block_contents,
+                    chain,
+                    &network_tx,
+                    log,
+                    validation_level.broadcast_validation,
+                )
+                .await
+                {
+                    Ok(()) => warp::reply().into_response(),
+                    Err(e) => match warp_utils::reject::handle_rejection(e).await {
+                        Ok(reply) => reply.into_response(),
+                        Err(_) => warp::reply::with_status(
+                            StatusCode::INTERNAL_SERVER_ERROR,
+                            eth2::StatusCode::INTERNAL_SERVER_ERROR,
+                        )
+                        .into_response(),
+                    },
+                }
             },
         );
 
@@ -2369,24 +2458,41 @@ pub fn serve<T: BeaconChainTypes>(
         .and(warp::path("health"))
         .and(warp::path::end())
         .and(network_globals.clone())
-        .and_then(|network_globals: Arc<NetworkGlobals<T::EthSpec>>| {
-            blocking_response_task(move || match *network_globals.sync_state.read() {
-                SyncState::SyncingFinalized { .. }
-                | SyncState::SyncingHead { .. }
-                | SyncState::SyncTransition
-                | SyncState::BackFillSyncing { .. } => Ok(warp::reply::with_status(
-                    warp::reply(),
-                    warp::http::StatusCode::PARTIAL_CONTENT,
-                )),
-                SyncState::Synced => Ok(warp::reply::with_status(
-                    warp::reply(),
-                    warp::http::StatusCode::OK,
-                )),
-                SyncState::Stalled => Err(warp_utils::reject::not_synced(
-                    "sync stalled, beacon chain may not yet be initialized.".to_string(),
-                )),
-            })
-        });
+        .and(chain_filter.clone())
+        .and_then(
+            |network_globals: Arc<NetworkGlobals<T::EthSpec>>, chain: Arc<BeaconChain<T>>| {
+                async move {
+                    let el_offline = if let Some(el) = &chain.execution_layer {
+                        el.is_offline_or_erroring().await
+                    } else {
+                        true
+                    };
+
+                    blocking_response_task(move || {
+                        let is_optimistic = chain
+                            .is_optimistic_or_invalid_head()
+                            .map_err(warp_utils::reject::beacon_chain_error)?;
+
+                        let is_syncing = !network_globals.sync_state.read().is_synced();
+
+                        if el_offline {
+                            Err(warp_utils::reject::not_synced("execution layer is offline".to_string()))
+                        } else if is_syncing || is_optimistic {
+                            Ok(warp::reply::with_status(
+                                warp::reply(),
+                                warp::http::StatusCode::PARTIAL_CONTENT,
+                            ))
+                        } else {
+                            Ok(warp::reply::with_status(
+                                warp::reply(),
+                                warp::http::StatusCode::OK,
+                            ))
+                        }
+                    })
+                    .await
+                }
+            },
+        );
 
     // GET node/peers/{peer_id}
     let get_node_peers_by_id = eth_v1
@@ -3866,6 +3972,8 @@ pub fn serve<T: BeaconChainTypes>(
             warp::post().and(
                 post_beacon_blocks
                     .uor(post_beacon_blinded_blocks)
+                    .uor(post_beacon_blocks_v2)
+                    .uor(post_beacon_blinded_blocks_v2)
                     .uor(post_beacon_pool_attestations)
                     .uor(post_beacon_pool_attester_slashings)
                     .uor(post_beacon_pool_proposer_slashings)
diff --git a/beacon_node/http_api/src/publish_blocks.rs b/beacon_node/http_api/src/publish_blocks.rs
index b8d940ff5..3a4875113 100644
--- a/beacon_node/http_api/src/publish_blocks.rs
+++ b/beacon_node/http_api/src/publish_blocks.rs
@@ -2,9 +2,12 @@ use crate::metrics;
 
 use beacon_chain::blob_verification::{AsBlock, BlockWrapper};
 use beacon_chain::validator_monitor::{get_block_delay_ms, timestamp_now};
-use beacon_chain::{AvailabilityProcessingStatus, NotifyExecutionLayer};
-use beacon_chain::{BeaconChain, BeaconChainTypes, BlockError};
+use beacon_chain::{
+    BeaconChain, BeaconChainError, BeaconChainTypes, BlockError, GossipVerifiedBlock,
+    NotifyExecutionLayer, AvailabilityProcessingStatus
+};
 use eth2::types::SignedBlockContents;
+use eth2::types::BroadcastValidation;
 use execution_layer::ProvenancedPayload;
 use lighthouse_network::PubsubMessage;
 use network::NetworkMessage;
@@ -29,6 +32,16 @@ pub enum ProvenancedBlock<T: EthSpec> {
     Builder(SignedBlockContents<T, FullPayload<T>>),
 }
 
+impl<T: EthSpec> ProvenancedBlock<T> {
+    pub fn local(block: Arc<SignedBeaconBlock<T>>) -> Self {
+        Self::Local(block)
+    }
+
+    pub fn builder(block: Arc<SignedBeaconBlock<T>>) -> Self {
+        Self::Builder(block)
+    }
+}
+
 /// Handles a request from the HTTP API for full blocks.
 pub async fn publish_block<T: BeaconChainTypes>(
     block_root: Option<Hash256>,
@@ -36,6 +49,7 @@ pub async fn publish_block<T: BeaconChainTypes>(
     chain: Arc<BeaconChain<T>>,
     network_tx: &UnboundedSender<NetworkMessage<T::EthSpec>>,
     log: Logger,
+    validation_level: BroadcastValidation,
 ) -> Result<(), Rejection> {
     let seen_timestamp = timestamp_now();
     let (block, maybe_blobs, is_locally_built_block) = match provenanced_block {
@@ -48,17 +62,24 @@ pub async fn publish_block<T: BeaconChainTypes>(
             (Arc::new(block), maybe_blobs, false)
         }
     };
-    let delay = get_block_delay_ms(seen_timestamp, block.message(), &chain.slot_clock);
-
-    //FIXME(sean) have to move this to prior to publishing because it's included in the blobs sidecar message.
+    let beacon_block = block.clone();
+    let delay = get_block_delay_ms(seen_timestamp, beacon_block.message(), &chain.slot_clock);
+        //FIXME(sean) have to move this to prior to publishing because it's included in the blobs sidecar message.
     //this may skew metrics
     let block_root = block_root.unwrap_or_else(|| block.canonical_root());
-    debug!(
-        log,
-        "Signed block published to HTTP API";
-        "slot" => block.slot()
-    );
+    debug!(log, "Signed block received in HTTP API"; "slot" => beacon_block.slot());
 
+    /* actually publish a block */
+    let publish_block = move |block: Arc<SignedBeaconBlock<T::EthSpec>>,
+                              sender,
+                              log,
+                              seen_timestamp| {
+        let publish_timestamp = timestamp_now();
+        let publish_delay = publish_timestamp
+            .checked_sub(seen_timestamp)
+            .unwrap_or_else(|| Duration::from_secs(0));
+
+        info!(log, "Signed block published to network via HTTP API"; "slot" => block.slot(), "publish_delay" => ?publish_delay);
     // Send the block, regardless of whether or not it is valid. The API
     // specification is very clear that this is the desired behaviour.
     let wrapped_block: BlockWrapper<T::EthSpec> = match block.as_ref() {
@@ -88,13 +109,70 @@ pub async fn publish_block<T: BeaconChainTypes>(
             }
         }
     };
-    // Determine the delay after the start of the slot, register it with metrics.
+        let message = PubsubMessage::BeaconBlock(block);
+        crate::publish_pubsub_message(&sender, message)
+            .map_err(|_| BeaconChainError::UnableToPublish.into())
+    };
 
+    /* if we can form a `GossipVerifiedBlock`, we've passed our basic gossip checks */
+    let gossip_verified_block = GossipVerifiedBlock::new(block, &chain).map_err(|e| {
+        warn!(log, "Not publishing block, not gossip verified"; "slot" => beacon_block.slot(), "error" => ?e);
+        warp_utils::reject::custom_bad_request(e.to_string())
+    })?;
+
+    let block_root = block_root.unwrap_or(gossip_verified_block.block_root);
+
+    if let BroadcastValidation::Gossip = validation_level {
+        publish_block(
+            beacon_block.clone(),
+            network_tx.clone(),
+            log.clone(),
+            seen_timestamp,
+        )
+        .map_err(|_| warp_utils::reject::custom_server_error("unable to publish".into()))?;
+    }
+
+    /* only publish if gossip- and consensus-valid and equivocation-free */
+    let chain_clone = chain.clone();
+    let block_clone = beacon_block.clone();
+    let log_clone = log.clone();
+    let sender_clone = network_tx.clone();
+
+    let publish_fn = move || match validation_level {
+        BroadcastValidation::Gossip => Ok(()),
+        BroadcastValidation::Consensus => {
+            publish_block(block_clone, sender_clone, log_clone, seen_timestamp)
+        }
+        BroadcastValidation::ConsensusAndEquivocation => {
+            if chain_clone
+                .observed_block_producers
+                .read()
+                .proposer_has_been_observed(block_clone.message(), block_root)
+                .map_err(|e| BlockError::BeaconChainError(e.into()))?
+                .is_slashable()
+            {
+                warn!(
+                    log_clone,
+                    "Not publishing equivocating block";
+                    "slot" => block_clone.slot()
+                );
+                Err(BlockError::Slashable)
+            } else {
+                publish_block(block_clone, sender_clone, log_clone, seen_timestamp)
+            }
+        }
+    };
     let block_clone = wrapped_block.block_cloned();
     let slot = block_clone.message().slot();
     let proposer_index = block_clone.message().proposer_index();
+
     match chain
-        .process_block(block_root, wrapped_block, NotifyExecutionLayer::Yes)
+        .process_block(
+            block_root,
+            gossip_verified_block,
+            NotifyExecutionLayer::Yes,
+            publish_fn,
+        )
         .await
     {
         Ok(AvailabilityProcessingStatus::Imported(root)) => {
@@ -144,35 +222,32 @@ pub async fn publish_block<T: BeaconChainTypes>(
             );
             Err(warp_utils::reject::broadcast_without_import(msg))
         }
-        Err(BlockError::BlockIsAlreadyKnown) => {
-            info!(
-                log,
-                "Block from HTTP API already known";
-                "block" => ?block_root,
-                "slot" => slot,
-            );
-            Ok(())
+        Err(BlockError::BeaconChainError(BeaconChainError::UnableToPublish)) => {
+            Err(warp_utils::reject::custom_server_error(
+                "unable to publish to network channel".to_string(),
+            ))
         }
-        Err(BlockError::RepeatProposal { proposer, slot }) => {
-            warn!(
-                log,
-                "Block ignored due to repeat proposal";
-                "msg" => "this can happen when a VC uses fallback BNs. \
-                    whilst this is not necessarily an error, it can indicate issues with a BN \
-                    or between the VC and BN.",
-                "slot" => slot,
-                "proposer" => proposer,
-            );
+        Err(BlockError::Slashable) => Err(warp_utils::reject::custom_bad_request(
+            "proposal for this slot and proposer has already been seen".to_string(),
+        )),
+        Err(BlockError::BlockIsAlreadyKnown) => {
+            info!(log, "Block from HTTP API already known"; "block" => ?block_root);
             Ok(())
         }
         Err(e) => {
-            let msg = format!("{:?}", e);
-            error!(
-                log,
-                "Invalid block provided to HTTP API";
-                "reason" => &msg
-            );
-            Err(warp_utils::reject::broadcast_without_import(msg))
+            if let BroadcastValidation::Gossip = validation_level {
+                Err(warp_utils::reject::broadcast_without_import(format!("{e}")))
+            } else {
+                let msg = format!("{:?}", e);
+                error!(
+                    log,
+                    "Invalid block provided to HTTP API";
+                    "reason" => &msg
+                );
+                Err(warp_utils::reject::custom_bad_request(format!(
+                    "Invalid block: {e}"
+                )))
+            }
         }
     }
 }
@@ -184,21 +259,31 @@ pub async fn publish_blinded_block<T: BeaconChainTypes>(
     chain: Arc<BeaconChain<T>>,
     network_tx: &UnboundedSender<NetworkMessage<T::EthSpec>>,
     log: Logger,
+    validation_level: BroadcastValidation,
 ) -> Result<(), Rejection> {
     let block_root = block.canonical_root();
-    let full_block = reconstruct_block(chain.clone(), block_root, block, log.clone()).await?;
-    publish_block::<T>(Some(block_root), full_block, chain, network_tx, log).await
+    let full_block: ProvenancedBlock<T> =
+        reconstruct_block(chain.clone(), block_root, block, log.clone()).await?;
+    publish_block::<T>(
+        Some(block_root),
+        full_block,
+        chain,
+        network_tx,
+        log,
+        validation_level,
+    )
+    .await
 }
 
 /// Deconstruct the given blinded block, and construct a full block. This attempts to use the
 /// execution layer's payload cache, and if that misses, attempts a blind block proposal to retrieve
 /// the full payload.
-async fn reconstruct_block<T: BeaconChainTypes>(
+pub async fn reconstruct_block<T: BeaconChainTypes>(
     chain: Arc<BeaconChain<T>>,
     block_root: Hash256,
     block: SignedBeaconBlock<T::EthSpec, BlindedPayload<T::EthSpec>>,
     log: Logger,
-) -> Result<ProvenancedBlock<T::EthSpec>, Rejection> {
+) -> Result<ProvenancedBlock<T>, Rejection> {
     let full_payload_opt = if let Ok(payload_header) = block.message().body().execution_payload() {
         let el = chain.execution_layer.as_ref().ok_or_else(|| {
             warp_utils::reject::custom_server_error("Missing execution layer".to_string())
@@ -264,15 +349,15 @@ async fn reconstruct_block<T: BeaconChainTypes>(
         None => block
             .try_into_full_block(None)
             .map(SignedBlockContents::Block)
-            .map(ProvenancedBlock::Local),
+            .map(ProvenancedBlock::local),
         Some(ProvenancedPayload::Local(full_payload)) => block
             .try_into_full_block(Some(full_payload))
             .map(SignedBlockContents::Block)
-            .map(ProvenancedBlock::Local),
+            .map(ProvenancedBlock::local),
         Some(ProvenancedPayload::Builder(full_payload)) => block
             .try_into_full_block(Some(full_payload))
             .map(SignedBlockContents::Block)
-            .map(ProvenancedBlock::Builder),
+            .map(ProvenancedBlock::builder),
     }
     .ok_or_else(|| {
         warp_utils::reject::custom_server_error("Unable to add payload to block".to_string())
diff --git a/beacon_node/http_api/tests/broadcast_validation_tests.rs b/beacon_node/http_api/tests/broadcast_validation_tests.rs
new file mode 100644
index 000000000..4819dd99e
--- /dev/null
+++ b/beacon_node/http_api/tests/broadcast_validation_tests.rs
@@ -0,0 +1,1270 @@
+use beacon_chain::{
+    test_utils::{AttestationStrategy, BlockStrategy},
+    GossipVerifiedBlock,
+};
+use eth2::types::{BroadcastValidation, SignedBeaconBlock, SignedBlindedBeaconBlock};
+use http_api::test_utils::InteractiveTester;
+use http_api::{publish_blinded_block, publish_block, reconstruct_block, ProvenancedBlock};
+use tree_hash::TreeHash;
+use types::{Hash256, MainnetEthSpec, Slot};
+use warp::Rejection;
+use warp_utils::reject::CustomBadRequest;
+
+use eth2::reqwest::StatusCode;
+
+type E = MainnetEthSpec;
+
+/*
+ * We have the following test cases, which are duplicated for the blinded variant of the route:
+ *
+ * -  `broadcast_validation=gossip`
+ *   -  Invalid (400)
+ *   -  Full Pass (200)
+ *   -  Partial Pass (202)
+ *  -  `broadcast_validation=consensus`
+ *    -  Invalid (400)
+ *    -  Only gossip (400)
+ *    -  Only consensus pass (i.e., equivocates) (200)
+ *    -  Full pass (200)
+ *  -  `broadcast_validation=consensus_and_equivocation`
+ *    -  Invalid (400)
+ *    -  Invalid due to early equivocation (400)
+ *    -  Only gossip (400)
+ *    -  Only consensus (400)
+ *    -  Pass (200)
+ *
+ */
+
+/// This test checks that a block that is **invalid** from a gossip perspective gets rejected when using `broadcast_validation=gossip`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn gossip_invalid() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> = Some(BroadcastValidation::Gossip);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+
+    let chain_state_before = tester.harness.get_current_state();
+    let slot = chain_state_before.slot() + 1;
+
+    tester.harness.advance_slot();
+
+    let (block, _): (SignedBeaconBlock<E>, _) = tester
+        .harness
+        .make_block_with_modifier(chain_state_before, slot, |b| {
+            *b.state_root_mut() = Hash256::zero();
+            *b.parent_root_mut() = Hash256::zero();
+        })
+        .await;
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blocks_v2(&block, validation_level)
+        .await;
+    assert!(response.is_err());
+
+    let error_response: eth2::Error = response.err().unwrap();
+
+    /* mandated by Beacon API spec */
+    assert_eq!(error_response.status(), Some(StatusCode::BAD_REQUEST));
+
+    assert!(
+        matches!(error_response, eth2::Error::ServerMessage(err) if err.message == "BAD_REQUEST: NotFinalizedDescendant { block_parent_root: 0x0000000000000000000000000000000000000000000000000000000000000000 }".to_string())
+    );
+}
+
+/// This test checks that a block that is valid from a gossip perspective is accepted when using `broadcast_validation=gossip`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn gossip_partial_pass() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> = Some(BroadcastValidation::Gossip);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+
+    let chain_state_before = tester.harness.get_current_state();
+    let slot = chain_state_before.slot() + 1;
+
+    tester.harness.advance_slot();
+
+    let (block, _): (SignedBeaconBlock<E>, _) = tester
+        .harness
+        .make_block_with_modifier(chain_state_before, slot, |b| {
+            *b.state_root_mut() = Hash256::random()
+        })
+        .await;
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blocks_v2(&block, validation_level)
+        .await;
+    assert!(response.is_err());
+
+    let error_response = response.unwrap_err();
+
+    assert_eq!(error_response.status(), Some(StatusCode::ACCEPTED));
+}
+
+// This test checks that a block that is valid from both a gossip and consensus perspective is accepted when using `broadcast_validation=gossip`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn gossip_full_pass() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> = Some(BroadcastValidation::Gossip);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+    tester.harness.advance_slot();
+
+    let slot_a = Slot::new(num_initial);
+    let slot_b = slot_a + 1;
+
+    let state_a = tester.harness.get_current_state();
+    let (block, _): (SignedBeaconBlock<E>, _) = tester.harness.make_block(state_a, slot_b).await;
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blocks_v2(&block, validation_level)
+        .await;
+
+    assert!(response.is_ok());
+    assert!(tester
+        .harness
+        .chain
+        .block_is_known_to_fork_choice(&block.canonical_root()));
+}
+
+/// This test checks that a block that is **invalid** from a gossip perspective gets rejected when using `broadcast_validation=consensus`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn consensus_invalid() {
+    let validation_level: Option<BroadcastValidation> = Some(BroadcastValidation::Consensus);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+
+    let chain_state_before = tester.harness.get_current_state();
+    let slot = chain_state_before.slot() + 1;
+
+    tester.harness.advance_slot();
+
+    let (block, _): (SignedBeaconBlock<E>, _) = tester
+        .harness
+        .make_block_with_modifier(chain_state_before, slot, |b| {
+            *b.state_root_mut() = Hash256::zero();
+            *b.parent_root_mut() = Hash256::zero();
+        })
+        .await;
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blocks_v2(&block, validation_level)
+        .await;
+    assert!(response.is_err());
+
+    let error_response: eth2::Error = response.err().unwrap();
+
+    /* mandated by Beacon API spec */
+    assert_eq!(error_response.status(), Some(StatusCode::BAD_REQUEST));
+
+    assert!(
+        matches!(error_response, eth2::Error::ServerMessage(err) if err.message == "BAD_REQUEST: NotFinalizedDescendant { block_parent_root: 0x0000000000000000000000000000000000000000000000000000000000000000 }".to_string())
+    );
+}
+
+/// This test checks that a block that is only valid from a gossip perspective is rejected when using `broadcast_validation=consensus`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn consensus_gossip() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> = Some(BroadcastValidation::Consensus);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+    tester.harness.advance_slot();
+
+    let slot_a = Slot::new(num_initial);
+    let slot_b = slot_a + 1;
+
+    let state_a = tester.harness.get_current_state();
+    let (block, _): (SignedBeaconBlock<E>, _) = tester
+        .harness
+        .make_block_with_modifier(state_a, slot_b, |b| *b.state_root_mut() = Hash256::zero())
+        .await;
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blocks_v2(&block, validation_level)
+        .await;
+    assert!(response.is_err());
+
+    let error_response: eth2::Error = response.err().unwrap();
+
+    /* mandated by Beacon API spec */
+    assert_eq!(error_response.status(), Some(StatusCode::BAD_REQUEST));
+
+    assert!(
+        matches!(error_response, eth2::Error::ServerMessage(err) if err.message == "BAD_REQUEST: Invalid block: StateRootMismatch { block: 0x0000000000000000000000000000000000000000000000000000000000000000, local: 0xfc675d642ff7a06458eb33c7d7b62a5813e34d1b2bb1aee3e395100b579da026 }".to_string())
+    );
+}
+
+/// This test checks that a block that is valid from both a gossip and consensus perspective, but nonetheless equivocates, is accepted when using `broadcast_validation=consensus`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn consensus_partial_pass_only_consensus() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> = Some(BroadcastValidation::Consensus);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+    let test_logger = tester.harness.logger().clone();
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+    tester.harness.advance_slot();
+
+    let slot_a = Slot::new(num_initial);
+    let slot_b = slot_a + 1;
+
+    let state_a = tester.harness.get_current_state();
+    let (block_a, state_after_a): (SignedBeaconBlock<E>, _) =
+        tester.harness.make_block(state_a.clone(), slot_b).await;
+    let (block_b, state_after_b): (SignedBeaconBlock<E>, _) =
+        tester.harness.make_block(state_a, slot_b).await;
+
+    /* check for `make_block` curios */
+    assert_eq!(block_a.state_root(), state_after_a.tree_hash_root());
+    assert_eq!(block_b.state_root(), state_after_b.tree_hash_root());
+    assert_ne!(block_a.state_root(), block_b.state_root());
+
+    let gossip_block_b = GossipVerifiedBlock::new(block_b.clone().into(), &tester.harness.chain);
+    assert!(gossip_block_b.is_ok());
+    let gossip_block_a = GossipVerifiedBlock::new(block_a.clone().into(), &tester.harness.chain);
+    assert!(gossip_block_a.is_err());
+
+    /* submit `block_b` which should induce equivocation */
+    let channel = tokio::sync::mpsc::unbounded_channel();
+
+    let publication_result: Result<(), Rejection> = publish_block(
+        None,
+        ProvenancedBlock::local(gossip_block_b.unwrap()),
+        tester.harness.chain.clone(),
+        &channel.0,
+        test_logger,
+        validation_level.unwrap(),
+    )
+    .await;
+
+    assert!(publication_result.is_ok());
+    assert!(tester
+        .harness
+        .chain
+        .block_is_known_to_fork_choice(&block_b.canonical_root()));
+}
+
+/// This test checks that a block that is valid from both a gossip and consensus perspective is accepted when using `broadcast_validation=consensus`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn consensus_full_pass() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> = Some(BroadcastValidation::Consensus);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+    tester.harness.advance_slot();
+
+    let slot_a = Slot::new(num_initial);
+    let slot_b = slot_a + 1;
+
+    let state_a = tester.harness.get_current_state();
+    let (block, _): (SignedBeaconBlock<E>, _) = tester.harness.make_block(state_a, slot_b).await;
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blocks_v2(&block, validation_level)
+        .await;
+
+    assert!(response.is_ok());
+    assert!(tester
+        .harness
+        .chain
+        .block_is_known_to_fork_choice(&block.canonical_root()));
+}
+
+/// This test checks that a block that is **invalid** from a gossip perspective gets rejected when using `broadcast_validation=consensus_and_equivocation`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn equivocation_invalid() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> =
+        Some(BroadcastValidation::ConsensusAndEquivocation);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+
+    let chain_state_before = tester.harness.get_current_state();
+    let slot = chain_state_before.slot() + 1;
+
+    tester.harness.advance_slot();
+
+    let (block, _): (SignedBeaconBlock<E>, _) = tester
+        .harness
+        .make_block_with_modifier(chain_state_before, slot, |b| {
+            *b.state_root_mut() = Hash256::zero();
+            *b.parent_root_mut() = Hash256::zero();
+        })
+        .await;
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blocks_v2(&block, validation_level)
+        .await;
+    assert!(response.is_err());
+
+    let error_response: eth2::Error = response.err().unwrap();
+
+    /* mandated by Beacon API spec */
+    assert_eq!(error_response.status(), Some(StatusCode::BAD_REQUEST));
+
+    assert!(
+        matches!(error_response, eth2::Error::ServerMessage(err) if err.message == "BAD_REQUEST: NotFinalizedDescendant { block_parent_root: 0x0000000000000000000000000000000000000000000000000000000000000000 }".to_string())
+    );
+}
+
+/// This test checks that a block that is valid from both a gossip and consensus perspective is rejected when using `broadcast_validation=consensus_and_equivocation`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn equivocation_consensus_early_equivocation() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> =
+        Some(BroadcastValidation::ConsensusAndEquivocation);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+    tester.harness.advance_slot();
+
+    let slot_a = Slot::new(num_initial);
+    let slot_b = slot_a + 1;
+
+    let state_a = tester.harness.get_current_state();
+    let (block_a, state_after_a): (SignedBeaconBlock<E>, _) =
+        tester.harness.make_block(state_a.clone(), slot_b).await;
+    let (block_b, state_after_b): (SignedBeaconBlock<E>, _) =
+        tester.harness.make_block(state_a, slot_b).await;
+
+    /* check for `make_block` curios */
+    assert_eq!(block_a.state_root(), state_after_a.tree_hash_root());
+    assert_eq!(block_b.state_root(), state_after_b.tree_hash_root());
+    assert_ne!(block_a.state_root(), block_b.state_root());
+
+    /* submit `block_a` as valid */
+    assert!(tester
+        .client
+        .post_beacon_blocks_v2(&block_a, validation_level)
+        .await
+        .is_ok());
+    assert!(tester
+        .harness
+        .chain
+        .block_is_known_to_fork_choice(&block_a.canonical_root()));
+
+    /* submit `block_b` which should induce equivocation */
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blocks_v2(&block_b, validation_level)
+        .await;
+    assert!(response.is_err());
+
+    let error_response: eth2::Error = response.err().unwrap();
+
+    assert_eq!(error_response.status(), Some(StatusCode::BAD_REQUEST));
+
+    assert!(
+        matches!(error_response, eth2::Error::ServerMessage(err) if err.message ==  "BAD_REQUEST: Slashable".to_string())
+    );
+}
+
+/// This test checks that a block that is only valid from a gossip perspective is rejected when using `broadcast_validation=consensus_and_equivocation`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn equivocation_gossip() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> =
+        Some(BroadcastValidation::ConsensusAndEquivocation);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+    tester.harness.advance_slot();
+
+    let slot_a = Slot::new(num_initial);
+    let slot_b = slot_a + 1;
+
+    let state_a = tester.harness.get_current_state();
+    let (block, _): (SignedBeaconBlock<E>, _) = tester
+        .harness
+        .make_block_with_modifier(state_a, slot_b, |b| *b.state_root_mut() = Hash256::zero())
+        .await;
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blocks_v2(&block, validation_level)
+        .await;
+    assert!(response.is_err());
+
+    let error_response: eth2::Error = response.err().unwrap();
+
+    /* mandated by Beacon API spec */
+    assert_eq!(error_response.status(), Some(StatusCode::BAD_REQUEST));
+
+    assert!(
+        matches!(error_response, eth2::Error::ServerMessage(err) if err.message == "BAD_REQUEST: Invalid block: StateRootMismatch { block: 0x0000000000000000000000000000000000000000000000000000000000000000, local: 0xfc675d642ff7a06458eb33c7d7b62a5813e34d1b2bb1aee3e395100b579da026 }".to_string())
+    );
+}
+
+/// This test checks that a block that is valid from both a gossip and consensus perspective but that equivocates **late** is rejected when using `broadcast_validation=consensus_and_equivocation`.
+///
+/// This test is unique in that we can't actually test the HTTP API directly, but instead have to hook into the `publish_blocks` code manually. This is in order to handle the late equivocation case.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn equivocation_consensus_late_equivocation() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> =
+        Some(BroadcastValidation::ConsensusAndEquivocation);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+    let test_logger = tester.harness.logger().clone();
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+    tester.harness.advance_slot();
+
+    let slot_a = Slot::new(num_initial);
+    let slot_b = slot_a + 1;
+
+    let state_a = tester.harness.get_current_state();
+    let (block_a, state_after_a): (SignedBeaconBlock<E>, _) =
+        tester.harness.make_block(state_a.clone(), slot_b).await;
+    let (block_b, state_after_b): (SignedBeaconBlock<E>, _) =
+        tester.harness.make_block(state_a, slot_b).await;
+
+    /* check for `make_block` curios */
+    assert_eq!(block_a.state_root(), state_after_a.tree_hash_root());
+    assert_eq!(block_b.state_root(), state_after_b.tree_hash_root());
+    assert_ne!(block_a.state_root(), block_b.state_root());
+
+    let gossip_block_b = GossipVerifiedBlock::new(block_b.clone().into(), &tester.harness.chain);
+    assert!(gossip_block_b.is_ok());
+    let gossip_block_a = GossipVerifiedBlock::new(block_a.clone().into(), &tester.harness.chain);
+    assert!(gossip_block_a.is_err());
+
+    let channel = tokio::sync::mpsc::unbounded_channel();
+
+    let publication_result: Result<(), Rejection> = publish_block(
+        None,
+        ProvenancedBlock::local(gossip_block_b.unwrap()),
+        tester.harness.chain,
+        &channel.0,
+        test_logger,
+        validation_level.unwrap(),
+    )
+    .await;
+
+    assert!(publication_result.is_err());
+
+    let publication_error = publication_result.unwrap_err();
+
+    assert!(publication_error.find::<CustomBadRequest>().is_some());
+
+    assert_eq!(
+        *publication_error.find::<CustomBadRequest>().unwrap().0,
+        "proposal for this slot and proposer has already been seen".to_string()
+    );
+}
+
+/// This test checks that a block that is valid from both a gossip and consensus perspective (and does not equivocate) is accepted when using `broadcast_validation=consensus_and_equivocation`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn equivocation_full_pass() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> =
+        Some(BroadcastValidation::ConsensusAndEquivocation);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+    tester.harness.advance_slot();
+
+    let slot_a = Slot::new(num_initial);
+    let slot_b = slot_a + 1;
+
+    let state_a = tester.harness.get_current_state();
+    let (block, _): (SignedBeaconBlock<E>, _) = tester.harness.make_block(state_a, slot_b).await;
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blocks_v2(&block, validation_level)
+        .await;
+
+    assert!(response.is_ok());
+    assert!(tester
+        .harness
+        .chain
+        .block_is_known_to_fork_choice(&block.canonical_root()));
+}
+
+/// This test checks that a block that is **invalid** from a gossip perspective gets rejected when using `broadcast_validation=gossip`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn blinded_gossip_invalid() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> = Some(BroadcastValidation::Gossip);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+
+    let chain_state_before = tester.harness.get_current_state();
+    let slot = chain_state_before.slot() + 1;
+
+    tester.harness.advance_slot();
+
+    let (block, _): (SignedBeaconBlock<E>, _) = tester
+        .harness
+        .make_block_with_modifier(chain_state_before, slot, |b| {
+            *b.state_root_mut() = Hash256::zero();
+            *b.parent_root_mut() = Hash256::zero();
+        })
+        .await;
+
+    let blinded_block: SignedBlindedBeaconBlock<E> = block.into();
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blinded_blocks_v2(&blinded_block, validation_level)
+        .await;
+    assert!(response.is_err());
+
+    let error_response: eth2::Error = response.err().unwrap();
+
+    /* mandated by Beacon API spec */
+    assert_eq!(error_response.status(), Some(StatusCode::BAD_REQUEST));
+
+    assert!(
+        matches!(error_response, eth2::Error::ServerMessage(err) if err.message == "BAD_REQUEST: NotFinalizedDescendant { block_parent_root: 0x0000000000000000000000000000000000000000000000000000000000000000 }".to_string())
+    );
+}
+
+/// This test checks that a block that is valid from a gossip perspective is accepted when using `broadcast_validation=gossip`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn blinded_gossip_partial_pass() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> = Some(BroadcastValidation::Gossip);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+
+    let chain_state_before = tester.harness.get_current_state();
+    let slot = chain_state_before.slot() + 1;
+
+    tester.harness.advance_slot();
+
+    let (block, _): (SignedBeaconBlock<E>, _) = tester
+        .harness
+        .make_block_with_modifier(chain_state_before, slot, |b| {
+            *b.state_root_mut() = Hash256::zero()
+        })
+        .await;
+
+    let blinded_block: SignedBlindedBeaconBlock<E> = block.into();
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blinded_blocks_v2(&blinded_block, validation_level)
+        .await;
+    assert!(response.is_err());
+
+    let error_response = response.unwrap_err();
+
+    assert_eq!(error_response.status(), Some(StatusCode::ACCEPTED));
+}
+
+// This test checks that a block that is valid from both a gossip and consensus perspective is accepted when using `broadcast_validation=gossip`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn blinded_gossip_full_pass() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> = Some(BroadcastValidation::Gossip);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+    tester.harness.advance_slot();
+
+    let slot_a = Slot::new(num_initial);
+    let slot_b = slot_a + 1;
+
+    let state_a = tester.harness.get_current_state();
+    let (block, _): (SignedBlindedBeaconBlock<E>, _) =
+        tester.harness.make_blinded_block(state_a, slot_b).await;
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blinded_blocks_v2(&block, validation_level)
+        .await;
+
+    assert!(response.is_ok());
+    assert!(tester
+        .harness
+        .chain
+        .block_is_known_to_fork_choice(&block.canonical_root()));
+}
+
+/// This test checks that a block that is **invalid** from a gossip perspective gets rejected when using `broadcast_validation=consensus`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn blinded_consensus_invalid() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> = Some(BroadcastValidation::Consensus);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+
+    let chain_state_before = tester.harness.get_current_state();
+    let slot = chain_state_before.slot() + 1;
+
+    tester.harness.advance_slot();
+
+    let (block, _): (SignedBeaconBlock<E>, _) = tester
+        .harness
+        .make_block_with_modifier(chain_state_before, slot, |b| {
+            *b.state_root_mut() = Hash256::zero();
+            *b.parent_root_mut() = Hash256::zero();
+        })
+        .await;
+
+    let blinded_block: SignedBlindedBeaconBlock<E> = block.into();
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blinded_blocks_v2(&blinded_block, validation_level)
+        .await;
+    assert!(response.is_err());
+
+    let error_response: eth2::Error = response.err().unwrap();
+
+    /* mandated by Beacon API spec */
+    assert_eq!(error_response.status(), Some(StatusCode::BAD_REQUEST));
+
+    assert!(
+        matches!(error_response, eth2::Error::ServerMessage(err) if err.message == "BAD_REQUEST: NotFinalizedDescendant { block_parent_root: 0x0000000000000000000000000000000000000000000000000000000000000000 }".to_string())
+    );
+}
+
+/// This test checks that a block that is only valid from a gossip perspective is rejected when using `broadcast_validation=consensus`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn blinded_consensus_gossip() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> = Some(BroadcastValidation::Consensus);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+    tester.harness.advance_slot();
+
+    let slot_a = Slot::new(num_initial);
+    let slot_b = slot_a + 1;
+
+    let state_a = tester.harness.get_current_state();
+    let (block, _): (SignedBeaconBlock<E>, _) = tester
+        .harness
+        .make_block_with_modifier(state_a, slot_b, |b| *b.state_root_mut() = Hash256::zero())
+        .await;
+
+    let blinded_block: SignedBlindedBeaconBlock<E> = block.into();
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blinded_blocks_v2(&blinded_block, validation_level)
+        .await;
+    assert!(response.is_err());
+
+    let error_response: eth2::Error = response.err().unwrap();
+
+    /* mandated by Beacon API spec */
+    assert_eq!(error_response.status(), Some(StatusCode::BAD_REQUEST));
+
+    assert!(
+        matches!(error_response, eth2::Error::ServerMessage(err) if err.message == "BAD_REQUEST: Invalid block: StateRootMismatch { block: 0x0000000000000000000000000000000000000000000000000000000000000000, local: 0xfc675d642ff7a06458eb33c7d7b62a5813e34d1b2bb1aee3e395100b579da026 }".to_string())
+    );
+}
+
+/// This test checks that a block that is valid from both a gossip and consensus perspective is accepted when using `broadcast_validation=consensus`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn blinded_consensus_full_pass() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> = Some(BroadcastValidation::Consensus);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+    tester.harness.advance_slot();
+
+    let slot_a = Slot::new(num_initial);
+    let slot_b = slot_a + 1;
+
+    let state_a = tester.harness.get_current_state();
+    let (block, _): (SignedBlindedBeaconBlock<E>, _) =
+        tester.harness.make_blinded_block(state_a, slot_b).await;
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blinded_blocks_v2(&block, validation_level)
+        .await;
+
+    assert!(response.is_ok());
+    assert!(tester
+        .harness
+        .chain
+        .block_is_known_to_fork_choice(&block.canonical_root()));
+}
+
+/// This test checks that a block that is **invalid** from a gossip perspective gets rejected when using `broadcast_validation=consensus_and_equivocation`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn blinded_equivocation_invalid() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> =
+        Some(BroadcastValidation::ConsensusAndEquivocation);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+
+    let chain_state_before = tester.harness.get_current_state();
+    let slot = chain_state_before.slot() + 1;
+
+    tester.harness.advance_slot();
+
+    let (block, _): (SignedBeaconBlock<E>, _) = tester
+        .harness
+        .make_block_with_modifier(chain_state_before, slot, |b| {
+            *b.state_root_mut() = Hash256::zero();
+            *b.parent_root_mut() = Hash256::zero();
+        })
+        .await;
+
+    let blinded_block: SignedBlindedBeaconBlock<E> = block.into();
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blinded_blocks_v2(&blinded_block, validation_level)
+        .await;
+    assert!(response.is_err());
+
+    let error_response: eth2::Error = response.err().unwrap();
+
+    /* mandated by Beacon API spec */
+    assert_eq!(error_response.status(), Some(StatusCode::BAD_REQUEST));
+
+    assert!(
+        matches!(error_response, eth2::Error::ServerMessage(err) if err.message == "BAD_REQUEST: NotFinalizedDescendant { block_parent_root: 0x0000000000000000000000000000000000000000000000000000000000000000 }".to_string())
+    );
+}
+
+/// This test checks that a block that is valid from both a gossip and consensus perspective is rejected when using `broadcast_validation=consensus_and_equivocation`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn blinded_equivocation_consensus_early_equivocation() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> =
+        Some(BroadcastValidation::ConsensusAndEquivocation);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+    tester.harness.advance_slot();
+
+    let slot_a = Slot::new(num_initial);
+    let slot_b = slot_a + 1;
+
+    let state_a = tester.harness.get_current_state();
+    let (block_a, state_after_a): (SignedBlindedBeaconBlock<E>, _) = tester
+        .harness
+        .make_blinded_block(state_a.clone(), slot_b)
+        .await;
+    let (block_b, state_after_b): (SignedBlindedBeaconBlock<E>, _) =
+        tester.harness.make_blinded_block(state_a, slot_b).await;
+
+    /* check for `make_blinded_block` curios */
+    assert_eq!(block_a.state_root(), state_after_a.tree_hash_root());
+    assert_eq!(block_b.state_root(), state_after_b.tree_hash_root());
+    assert_ne!(block_a.state_root(), block_b.state_root());
+
+    /* submit `block_a` as valid */
+    assert!(tester
+        .client
+        .post_beacon_blinded_blocks_v2(&block_a, validation_level)
+        .await
+        .is_ok());
+    assert!(tester
+        .harness
+        .chain
+        .block_is_known_to_fork_choice(&block_a.canonical_root()));
+
+    /* submit `block_b` which should induce equivocation */
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blinded_blocks_v2(&block_b, validation_level)
+        .await;
+    assert!(response.is_err());
+
+    let error_response: eth2::Error = response.err().unwrap();
+
+    assert_eq!(error_response.status(), Some(StatusCode::BAD_REQUEST));
+
+    assert!(
+        matches!(error_response, eth2::Error::ServerMessage(err) if err.message ==  "BAD_REQUEST: Slashable".to_string())
+    );
+}
+
+/// This test checks that a block that is only valid from a gossip perspective is rejected when using `broadcast_validation=consensus_and_equivocation`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn blinded_equivocation_gossip() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> =
+        Some(BroadcastValidation::ConsensusAndEquivocation);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+    tester.harness.advance_slot();
+
+    let slot_a = Slot::new(num_initial);
+    let slot_b = slot_a + 1;
+
+    let state_a = tester.harness.get_current_state();
+    let (block, _): (SignedBeaconBlock<E>, _) = tester
+        .harness
+        .make_block_with_modifier(state_a, slot_b, |b| *b.state_root_mut() = Hash256::zero())
+        .await;
+
+    let blinded_block: SignedBlindedBeaconBlock<E> = block.into();
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blinded_blocks_v2(&blinded_block, validation_level)
+        .await;
+    assert!(response.is_err());
+
+    let error_response: eth2::Error = response.err().unwrap();
+
+    /* mandated by Beacon API spec */
+    assert_eq!(error_response.status(), Some(StatusCode::BAD_REQUEST));
+
+    assert!(
+        matches!(error_response, eth2::Error::ServerMessage(err) if err.message == "BAD_REQUEST: Invalid block: StateRootMismatch { block: 0x0000000000000000000000000000000000000000000000000000000000000000, local: 0xfc675d642ff7a06458eb33c7d7b62a5813e34d1b2bb1aee3e395100b579da026 }".to_string())
+    );
+}
+
+/// This test checks that a block that is valid from both a gossip and consensus perspective but that equivocates **late** is rejected when using `broadcast_validation=consensus_and_equivocation`.
+///
+/// This test is unique in that we can't actually test the HTTP API directly, but instead have to hook into the `publish_blocks` code manually. This is in order to handle the late equivocation case.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn blinded_equivocation_consensus_late_equivocation() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> =
+        Some(BroadcastValidation::ConsensusAndEquivocation);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+    let test_logger = tester.harness.logger().clone();
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+    tester.harness.advance_slot();
+
+    let slot_a = Slot::new(num_initial);
+    let slot_b = slot_a + 1;
+
+    let state_a = tester.harness.get_current_state();
+    let (block_a, state_after_a): (SignedBlindedBeaconBlock<E>, _) = tester
+        .harness
+        .make_blinded_block(state_a.clone(), slot_b)
+        .await;
+    let (block_b, state_after_b): (SignedBlindedBeaconBlock<E>, _) =
+        tester.harness.make_blinded_block(state_a, slot_b).await;
+
+    /* check for `make_blinded_block` curios */
+    assert_eq!(block_a.state_root(), state_after_a.tree_hash_root());
+    assert_eq!(block_b.state_root(), state_after_b.tree_hash_root());
+    assert_ne!(block_a.state_root(), block_b.state_root());
+
+    let unblinded_block_a = reconstruct_block(
+        tester.harness.chain.clone(),
+        block_a.state_root(),
+        block_a,
+        test_logger.clone(),
+    )
+    .await
+    .unwrap();
+    let unblinded_block_b = reconstruct_block(
+        tester.harness.chain.clone(),
+        block_b.clone().state_root(),
+        block_b.clone(),
+        test_logger.clone(),
+    )
+    .await
+    .unwrap();
+
+    let inner_block_a = match unblinded_block_a {
+        ProvenancedBlock::Local(a, _) => a,
+        ProvenancedBlock::Builder(a, _) => a,
+    };
+    let inner_block_b = match unblinded_block_b {
+        ProvenancedBlock::Local(b, _) => b,
+        ProvenancedBlock::Builder(b, _) => b,
+    };
+
+    let gossip_block_b = GossipVerifiedBlock::new(inner_block_b, &tester.harness.chain);
+    assert!(gossip_block_b.is_ok());
+    let gossip_block_a = GossipVerifiedBlock::new(inner_block_a, &tester.harness.chain);
+    assert!(gossip_block_a.is_err());
+
+    let channel = tokio::sync::mpsc::unbounded_channel();
+
+    let publication_result: Result<(), Rejection> = publish_blinded_block(
+        block_b,
+        tester.harness.chain,
+        &channel.0,
+        test_logger,
+        validation_level.unwrap(),
+    )
+    .await;
+
+    assert!(publication_result.is_err());
+
+    let publication_error: Rejection = publication_result.unwrap_err();
+
+    assert!(publication_error.find::<CustomBadRequest>().is_some());
+}
+
+/// This test checks that a block that is valid from both a gossip and consensus perspective (and does not equivocate) is accepted when using `broadcast_validation=consensus_and_equivocation`.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+pub async fn blinded_equivocation_full_pass() {
+    /* this test targets gossip-level validation */
+    let validation_level: Option<BroadcastValidation> =
+        Some(BroadcastValidation::ConsensusAndEquivocation);
+
+    // Validator count needs to be at least 32 or proposer boost gets set to 0 when computing
+    // `validator_count // 32`.
+    let validator_count = 64;
+    let num_initial: u64 = 31;
+    let tester = InteractiveTester::<E>::new(None, validator_count).await;
+
+    // Create some chain depth.
+    tester.harness.advance_slot();
+    tester
+        .harness
+        .extend_chain(
+            num_initial as usize,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+    tester.harness.advance_slot();
+
+    let slot_a = Slot::new(num_initial);
+    let slot_b = slot_a + 1;
+
+    let state_a = tester.harness.get_current_state();
+    let (block, _): (SignedBlindedBeaconBlock<E>, _) =
+        tester.harness.make_blinded_block(state_a, slot_b).await;
+
+    let response: Result<(), eth2::Error> = tester
+        .client
+        .post_beacon_blocks_v2(&block, validation_level)
+        .await;
+
+    assert!(response.is_ok());
+    assert!(tester
+        .harness
+        .chain
+        .block_is_known_to_fork_choice(&block.canonical_root()));
+}
diff --git a/beacon_node/http_api/tests/main.rs b/beacon_node/http_api/tests/main.rs
index f5916d850..e0636424e 100644
--- a/beacon_node/http_api/tests/main.rs
+++ b/beacon_node/http_api/tests/main.rs
@@ -1,5 +1,6 @@
 #![cfg(not(debug_assertions))] // Tests are too slow in debug.
 
+pub mod broadcast_validation_tests;
 pub mod fork_tests;
 pub mod interactive_tests;
 pub mod status_tests;
diff --git a/beacon_node/http_api/tests/status_tests.rs b/beacon_node/http_api/tests/status_tests.rs
index 04df2379b..664c5f2ea 100644
--- a/beacon_node/http_api/tests/status_tests.rs
+++ b/beacon_node/http_api/tests/status_tests.rs
@@ -3,6 +3,7 @@ use beacon_chain::{
     test_utils::{AttestationStrategy, BlockStrategy, SyncCommitteeStrategy},
     BlockError,
 };
+use eth2::StatusCode;
 use execution_layer::{PayloadStatusV1, PayloadStatusV1Status};
 use http_api::test_utils::InteractiveTester;
 use types::{EthSpec, ExecPayload, ForkName, MinimalEthSpec, Slot};
@@ -149,3 +150,82 @@ async fn el_error_on_new_payload() {
     assert_eq!(api_response.is_optimistic, Some(false));
     assert_eq!(api_response.is_syncing, false);
 }
+
+/// Check `node health` endpoint when the EL is offline.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn node_health_el_offline() {
+    let num_blocks = E::slots_per_epoch() / 2;
+    let num_validators = E::slots_per_epoch();
+    let tester = post_merge_tester(num_blocks, num_validators).await;
+    let harness = &tester.harness;
+    let mock_el = harness.mock_execution_layer.as_ref().unwrap();
+
+    // EL offline
+    mock_el.server.set_syncing_response(Err("offline".into()));
+    mock_el.el.upcheck().await;
+
+    let status = tester.client.get_node_health().await;
+    match status {
+        Ok(_) => {
+            panic!("should return 503 error status code");
+        }
+        Err(e) => {
+            assert_eq!(e.status().unwrap(), 503);
+        }
+    }
+}
+
+/// Check `node health` endpoint when the EL is online and synced.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn node_health_el_online_and_synced() {
+    let num_blocks = E::slots_per_epoch() / 2;
+    let num_validators = E::slots_per_epoch();
+    let tester = post_merge_tester(num_blocks, num_validators).await;
+    let harness = &tester.harness;
+    let mock_el = harness.mock_execution_layer.as_ref().unwrap();
+
+    // EL synced
+    mock_el.server.set_syncing_response(Ok(false));
+    mock_el.el.upcheck().await;
+
+    let status = tester.client.get_node_health().await;
+    match status {
+        Ok(response) => {
+            assert_eq!(response, StatusCode::OK);
+        }
+        Err(_) => {
+            panic!("should return 200 status code");
+        }
+    }
+}
+
+/// Check `node health` endpoint when the EL is online but not synced.
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn node_health_el_online_and_not_synced() {
+    let num_blocks = E::slots_per_epoch() / 2;
+    let num_validators = E::slots_per_epoch();
+    let tester = post_merge_tester(num_blocks, num_validators).await;
+    let harness = &tester.harness;
+    let mock_el = harness.mock_execution_layer.as_ref().unwrap();
+
+    // EL not synced
+    harness.advance_slot();
+    mock_el.server.all_payloads_syncing(true);
+    harness
+        .extend_chain(
+            1,
+            BlockStrategy::OnCanonicalHead,
+            AttestationStrategy::AllValidators,
+        )
+        .await;
+
+    let status = tester.client.get_node_health().await;
+    match status {
+        Ok(response) => {
+            assert_eq!(response, StatusCode::PARTIAL_CONTENT);
+        }
+        Err(_) => {
+            panic!("should return 206 status code");
+        }
+    }
+}
diff --git a/beacon_node/http_api/tests/tests.rs b/beacon_node/http_api/tests/tests.rs
index 491c55845..9d35c710a 100644
--- a/beacon_node/http_api/tests/tests.rs
+++ b/beacon_node/http_api/tests/tests.rs
@@ -8,7 +8,7 @@ use eth2::{
     mixin::{RequestAccept, ResponseForkName, ResponseOptional},
     reqwest::RequestBuilder,
     types::{BlockId as CoreBlockId, ForkChoiceNode, StateId as CoreStateId, *},
-    BeaconNodeHttpClient, Error, StatusCode, Timeouts,
+    BeaconNodeHttpClient, Error, Timeouts,
 };
 use execution_layer::test_utils::TestingBuilder;
 use execution_layer::test_utils::DEFAULT_BUILDER_THRESHOLD_WEI;
@@ -160,7 +160,7 @@ impl ApiTester {
 
         // `make_block` adds random graffiti, so this will produce an alternate block
         let (reorg_block, _reorg_state) = harness
-            .make_block(head.beacon_state.clone(), harness.chain.slot().unwrap())
+            .make_block(head.beacon_state.clone(), harness.chain.slot().unwrap() + 1)
             .await;
         let reorg_block = SignedBlockContents::from(reorg_block);
 
@@ -1252,18 +1252,23 @@ impl ApiTester {
     }
 
     pub async fn test_post_beacon_blocks_invalid(mut self) -> Self {
-        let mut next_block = self.next_block.clone().deconstruct().0;
-        *next_block.message_mut().proposer_index_mut() += 1;
-
-        assert!(self
-            .client
-            .post_beacon_blocks(&SignedBlockContents::from(next_block))
+        let block = self
+            .harness
+            .make_block_with_modifier(
+                self.harness.get_current_state(),
+                self.harness.get_current_slot(),
+                |b| {
+                    *b.state_root_mut() = Hash256::zero();
+                },
+            )
             .await
-            .is_err());
+            .0;
+
+        assert!(self.client.post_beacon_blocks(&SignedBlockContents::from(block)).await.is_err());
 
         assert!(
             self.network_rx.network_recv.recv().await.is_some(),
-            "invalid blocks should be sent to network"
+            "gossip valid blocks should be sent to network"
         );
 
         self
@@ -1761,9 +1766,15 @@ impl ApiTester {
     }
 
     pub async fn test_get_node_health(self) -> Self {
-        let status = self.client.get_node_health().await.unwrap();
-        assert_eq!(status, StatusCode::OK);
-
+        let status = self.client.get_node_health().await;
+        match status {
+            Ok(_) => {
+                panic!("should return 503 error status code");
+            }
+            Err(e) => {
+                assert_eq!(e.status().unwrap(), 503);
+            }
+        }
         self
     }
 
@@ -4142,7 +4153,7 @@ impl ApiTester {
             .unwrap();
 
         let expected_reorg = EventKind::ChainReorg(SseChainReorg {
-            slot: self.next_block.signed_block().slot(),
+            slot: self.reorg_block.slot(),
             depth: 1,
             old_head_block: self.next_block.signed_block().canonical_root(),
             old_head_state: self.next_block.signed_block().state_root(),
@@ -4156,6 +4167,8 @@ impl ApiTester {
             execution_optimistic: false,
         });
 
+        self.harness.advance_slot();
+
         self.client
             .post_beacon_blocks(&self.reorg_block)
             .await
diff --git a/beacon_node/network/src/beacon_processor/mod.rs b/beacon_node/network/src/beacon_processor/mod.rs
index c2e43e921..e051b1330 100644
--- a/beacon_node/network/src/beacon_processor/mod.rs
+++ b/beacon_node/network/src/beacon_processor/mod.rs
@@ -836,6 +836,24 @@ impl<T: BeaconChainTypes> std::convert::From<ReadyWork<T>> for WorkEvent<T> {
     }
 }
 
+pub struct BeaconProcessorSend<T: BeaconChainTypes>(pub mpsc::Sender<WorkEvent<T>>);
+
+impl<T: BeaconChainTypes> BeaconProcessorSend<T> {
+    pub fn try_send(&self, message: WorkEvent<T>) -> Result<(), Box<TrySendError<WorkEvent<T>>>> {
+        let work_type = message.work_type();
+        match self.0.try_send(message) {
+            Ok(res) => Ok(res),
+            Err(e) => {
+                metrics::inc_counter_vec(
+                    &metrics::BEACON_PROCESSOR_SEND_ERROR_PER_WORK_TYPE,
+                    &[work_type],
+                );
+                Err(Box::new(e))
+            }
+        }
+    }
+}
+
 /// A consensus message (or multiple) from the network that requires processing.
 #[derive(Derivative)]
 #[derivative(Debug(bound = "T: BeaconChainTypes"))]
diff --git a/beacon_node/network/src/beacon_processor/worker/gossip_methods.rs b/beacon_node/network/src/beacon_processor/worker/gossip_methods.rs
index 77418b23c..bd663be96 100644
--- a/beacon_node/network/src/beacon_processor/worker/gossip_methods.rs
+++ b/beacon_node/network/src/beacon_processor/worker/gossip_methods.rs
@@ -929,6 +929,20 @@ impl<T: BeaconChainTypes> Worker<T> {
 
                 verified_block
             }
+            Err(e @ BlockError::Slashable) => {
+                warn!(
+                    self.log,
+                    "Received equivocating block from peer";
+                    "error" => ?e
+                );
+                /* punish peer for submitting an equivocation, but not too harshly as honest peers may conceivably forward equivocating blocks to us from time to time */
+                self.gossip_penalize_peer(
+                    peer_id,
+                    PeerAction::MidToleranceError,
+                    "gossip_block_mid",
+                );
+                return None;
+            }
             Err(BlockError::ParentUnknown(block)) => {
                 debug!(
                     self.log,
@@ -950,7 +964,6 @@ impl<T: BeaconChainTypes> Worker<T> {
             Err(e @ BlockError::FutureSlot { .. })
             | Err(e @ BlockError::WouldRevertFinalizedSlot { .. })
             | Err(e @ BlockError::BlockIsAlreadyKnown)
-            | Err(e @ BlockError::RepeatProposal { .. })
             | Err(e @ BlockError::NotFinalizedDescendant { .. }) => {
                 debug!(self.log, "Could not verify block for gossip. Ignoring the block";
                             "error" => %e);
@@ -1103,7 +1116,12 @@ impl<T: BeaconChainTypes> Worker<T> {
 
         let result = self
             .chain
-            .process_block(block_root, verified_block, NotifyExecutionLayer::Yes)
+            .process_block(
+                block_root,
+                verified_block,
+                NotifyExecutionLayer::Yes,
+                || Ok(()),
+            )
             .await;
 
         match &result {
diff --git a/beacon_node/network/src/beacon_processor/worker/sync_methods.rs b/beacon_node/network/src/beacon_processor/worker/sync_methods.rs
index 45c3e5168..56630c3bc 100644
--- a/beacon_node/network/src/beacon_processor/worker/sync_methods.rs
+++ b/beacon_node/network/src/beacon_processor/worker/sync_methods.rs
@@ -103,33 +103,21 @@ impl<T: BeaconChainTypes> Worker<T> {
             });
 
         // Checks if a block from this proposer is already known.
-        let proposal_already_known = || {
+        let block_equivocates = || {
             match self
                 .chain
                 .observed_block_producers
                 .read()
-                .proposer_has_been_observed(block.message())
+                .proposer_has_been_observed(block.message(), block.canonical_root())
             {
-                Ok(is_observed) => is_observed,
-                // Both of these blocks will be rejected, so reject them now rather
+                Ok(seen_status) => seen_status.is_slashable(),
+                //Both of these blocks will be rejected, so reject them now rather
                 // than re-queuing them.
                 Err(ObserveError::FinalizedBlock { .. })
                 | Err(ObserveError::ValidatorIndexTooHigh { .. }) => false,
             }
         };
 
-        // Returns `true` if the block is already known to fork choice. Notably,
-        // this will return `false` for blocks that we've already imported but
-        // ancestors of the finalized checkpoint. That should not be an issue
-        // for our use here since finalized blocks will always be late and won't
-        // be requeued anyway.
-        let block_is_already_known = || {
-            self.chain
-                .canonical_head
-                .fork_choice_read_lock()
-                .contains_block(&block_root)
-        };
-
         // If we've already seen a block from this proposer *and* the block
         // arrived before the attestation deadline, requeue it to ensure it is
         // imported late enough that it won't receive a proposer boost.
@@ -137,7 +125,7 @@ impl<T: BeaconChainTypes> Worker<T> {
         // Don't requeue blocks if they're already known to fork choice, just
         // push them through to block processing so they can be handled through
         // the normal channels.
-        if !block_is_late && proposal_already_known() && !block_is_already_known() {
+        if !block_is_late && block_equivocates() {
             debug!(
                 self.log,
                 "Delaying processing of duplicate RPC block";
@@ -171,7 +159,7 @@ impl<T: BeaconChainTypes> Worker<T> {
 
         let result = self
             .chain
-            .process_block(block_root, block, NotifyExecutionLayer::Yes)
+            .process_block(block_root, block, NotifyExecutionLayer::Yes, || Ok(()))
             .await;
 
         metrics::inc_counter(&metrics::BEACON_PROCESSOR_RPC_BLOCK_IMPORTED_TOTAL);
diff --git a/beacon_node/network/src/metrics.rs b/beacon_node/network/src/metrics.rs
index 20a530ce8..62e59d14e 100644
--- a/beacon_node/network/src/metrics.rs
+++ b/beacon_node/network/src/metrics.rs
@@ -301,6 +301,12 @@ lazy_static! {
             "Gossipsub light_client_optimistic_update errors per error type",
             &["type"]
         );
+    pub static ref BEACON_PROCESSOR_SEND_ERROR_PER_WORK_TYPE: Result<IntCounterVec> =
+        try_create_int_counter_vec(
+            "beacon_processor_send_error_per_work_type",
+            "Total number of beacon processor send error per work type",
+            &["type"]
+        );
 
 
     /*
diff --git a/beacon_node/network/src/router.rs b/beacon_node/network/src/router.rs
index e9a4d1e3c..aeecb507d 100644
--- a/beacon_node/network/src/router.rs
+++ b/beacon_node/network/src/router.rs
@@ -6,7 +6,8 @@
 #![allow(clippy::unit_arg)]
 
 use crate::beacon_processor::{
-    BeaconProcessor, InvalidBlockStorage, WorkEvent as BeaconWorkEvent, MAX_WORK_EVENT_QUEUE_LEN,
+    BeaconProcessor, BeaconProcessorSend, InvalidBlockStorage, WorkEvent as BeaconWorkEvent,
+    MAX_WORK_EVENT_QUEUE_LEN,
 };
 use crate::error;
 use crate::service::{NetworkMessage, RequestId};
@@ -14,11 +15,14 @@ use crate::status::status_message;
 use crate::sync::manager::RequestId as SyncId;
 use crate::sync::SyncMessage;
 use beacon_chain::{BeaconChain, BeaconChainTypes};
-use futures::{future, StreamExt};
-
-use lighthouse_network::{rpc::*, PubsubMessage};
-use lighthouse_network::{MessageId, NetworkGlobals, PeerId, PeerRequestId, Request, Response};
-use slog::{debug, error, o, trace, warn};
+use futures::prelude::*;
+use lighthouse_network::rpc::*;
+use lighthouse_network::{
+    MessageId, NetworkGlobals, PeerId, PeerRequestId, PubsubMessage, Request, Response,
+};
+use logging::TimeLatch;
+use slog::{debug, o, trace};
+use slog::{error, warn};
 use std::cmp;
 use std::sync::Arc;
 use std::time::{Duration, SystemTime, UNIX_EPOCH};
@@ -37,9 +41,11 @@ pub struct Router<T: BeaconChainTypes> {
     /// A network context to return and handle RPC requests.
     network: HandlerNetworkContext<T::EthSpec>,
     /// A multi-threaded, non-blocking processor for applying messages to the beacon chain.
-    beacon_processor_send: mpsc::Sender<BeaconWorkEvent<T>>,
+    beacon_processor_send: BeaconProcessorSend<T>,
     /// The `Router` logger.
     log: slog::Logger,
+    /// Provides de-bounce functionality for logging.
+    logger_debounce: TimeLatch,
 }
 
 /// Types of messages the router can receive.
@@ -99,7 +105,7 @@ impl<T: BeaconChainTypes> Router<T> {
             beacon_chain.clone(),
             network_globals.clone(),
             network_send.clone(),
-            beacon_processor_send.clone(),
+            BeaconProcessorSend(beacon_processor_send.clone()),
             sync_logger,
         );
 
@@ -123,8 +129,9 @@ impl<T: BeaconChainTypes> Router<T> {
             chain: beacon_chain,
             sync_send,
             network: HandlerNetworkContext::new(network_send, log.clone()),
-            beacon_processor_send,
+            beacon_processor_send: BeaconProcessorSend(beacon_processor_send),
             log: message_handler_log,
+            logger_debounce: TimeLatch::default(),
         };
 
         // spawn handler task and move the message handler instance into the spawned thread
@@ -570,12 +577,15 @@ impl<T: BeaconChainTypes> Router<T> {
         self.beacon_processor_send
             .try_send(work)
             .unwrap_or_else(|e| {
-                let work_type = match &e {
+                let work_type = match &*e {
                     mpsc::error::TrySendError::Closed(work)
                     | mpsc::error::TrySendError::Full(work) => work.work_type(),
                 };
-                error!(&self.log, "Unable to send message to the beacon processor";
-                    "error" => %e, "type" => work_type)
+
+                if self.logger_debounce.elapsed() {
+                    error!(&self.log, "Unable to send message to the beacon processor";
+                        "error" => %e, "type" => work_type)
+                }
             })
     }
 }
diff --git a/beacon_node/network/src/sync/block_lookups/tests.rs b/beacon_node/network/src/sync/block_lookups/tests.rs
index ea6fee0af..bf7ac2776 100644
--- a/beacon_node/network/src/sync/block_lookups/tests.rs
+++ b/beacon_node/network/src/sync/block_lookups/tests.rs
@@ -1,6 +1,7 @@
 #![cfg(feature = "spec-minimal")]
 use std::sync::Arc;
 
+use crate::beacon_processor::BeaconProcessorSend;
 use crate::service::RequestId;
 use crate::sync::manager::RequestId as SyncId;
 use crate::NetworkMessage;
@@ -80,7 +81,7 @@ impl TestRig {
             SyncNetworkContext::new(
                 network_tx,
                 globals,
-                beacon_processor_tx,
+                BeaconProcessorSend(beacon_processor_tx),
                 chain,
                 log.new(slog::o!("component" => "network_context")),
             )
diff --git a/beacon_node/network/src/sync/manager.rs b/beacon_node/network/src/sync/manager.rs
index be2ecf850..2965de8e4 100644
--- a/beacon_node/network/src/sync/manager.rs
+++ b/beacon_node/network/src/sync/manager.rs
@@ -38,7 +38,7 @@ use super::block_lookups::{BlockLookups, PeerShouldHave};
 use super::network_context::{BlockOrBlob, SyncNetworkContext};
 use super::peer_sync_info::{remote_sync_type, PeerSyncType};
 use super::range_sync::{RangeSync, RangeSyncType, EPOCHS_PER_BATCH};
-use crate::beacon_processor::{ChainSegmentProcessId, WorkEvent as BeaconWorkEvent};
+use crate::beacon_processor::{BeaconProcessorSend, ChainSegmentProcessId};
 use crate::service::NetworkMessage;
 use crate::status::ToStatusMessage;
 use crate::sync::block_lookups::delayed_lookup;
@@ -238,7 +238,7 @@ pub fn spawn<T: BeaconChainTypes>(
     beacon_chain: Arc<BeaconChain<T>>,
     network_globals: Arc<NetworkGlobals<T::EthSpec>>,
     network_send: mpsc::UnboundedSender<NetworkMessage<T::EthSpec>>,
-    beacon_processor_send: mpsc::Sender<BeaconWorkEvent<T>>,
+    beacon_processor_send: BeaconProcessorSend<T>,
     log: slog::Logger,
 ) -> mpsc::UnboundedSender<SyncMessage<T::EthSpec>> {
     assert!(
diff --git a/beacon_node/network/src/sync/network_context.rs b/beacon_node/network/src/sync/network_context.rs
index 5f5c1bcf3..7cdc9a29b 100644
--- a/beacon_node/network/src/sync/network_context.rs
+++ b/beacon_node/network/src/sync/network_context.rs
@@ -4,7 +4,7 @@
 use super::block_sidecar_coupling::BlocksAndBlobsRequestInfo;
 use super::manager::{Id, RequestId as SyncRequestId};
 use super::range_sync::{BatchId, ByRangeRequestType, ChainId};
-use crate::beacon_processor::WorkEvent;
+use crate::beacon_processor::BeaconProcessorSend;
 use crate::service::{NetworkMessage, RequestId};
 use crate::status::ToStatusMessage;
 use crate::sync::block_lookups::{BlobRequestId, BlockRequestId};
@@ -60,7 +60,7 @@ pub struct SyncNetworkContext<T: BeaconChainTypes> {
     execution_engine_state: EngineState,
 
     /// Channel to send work to the beacon processor.
-    beacon_processor_send: mpsc::Sender<WorkEvent<T>>,
+    beacon_processor_send: BeaconProcessorSend<T>,
 
     pub chain: Arc<BeaconChain<T>>,
 
@@ -90,7 +90,7 @@ impl<T: BeaconChainTypes> SyncNetworkContext<T> {
     pub fn new(
         network_send: mpsc::UnboundedSender<NetworkMessage<T::EthSpec>>,
         network_globals: Arc<NetworkGlobals<T::EthSpec>>,
-        beacon_processor_send: mpsc::Sender<WorkEvent<T>>,
+        beacon_processor_send: BeaconProcessorSend<T>,
         chain: Arc<BeaconChain<T>>,
         log: slog::Logger,
     ) -> Self {
@@ -564,12 +564,12 @@ impl<T: BeaconChainTypes> SyncNetworkContext<T> {
         })
     }
 
-    pub fn processor_channel_if_enabled(&self) -> Option<&mpsc::Sender<WorkEvent<T>>> {
+    pub fn processor_channel_if_enabled(&self) -> Option<&BeaconProcessorSend<T>> {
         self.is_execution_engine_online()
             .then_some(&self.beacon_processor_send)
     }
 
-    pub fn processor_channel(&self) -> &mpsc::Sender<WorkEvent<T>> {
+    pub fn processor_channel(&self) -> &BeaconProcessorSend<T> {
         &self.beacon_processor_send
     }
 
diff --git a/beacon_node/network/src/sync/range_sync/range.rs b/beacon_node/network/src/sync/range_sync/range.rs
index b0b99e3ca..186f69264 100644
--- a/beacon_node/network/src/sync/range_sync/range.rs
+++ b/beacon_node/network/src/sync/range_sync/range.rs
@@ -381,7 +381,7 @@ where
 mod tests {
     use super::*;
 
-    use crate::beacon_processor::WorkEvent as BeaconWorkEvent;
+    use crate::beacon_processor::{BeaconProcessorSend, WorkEvent as BeaconWorkEvent};
     use crate::service::RequestId;
     use crate::NetworkMessage;
     use beacon_chain::{
@@ -610,7 +610,7 @@ mod tests {
         let cx = SyncNetworkContext::new(
             network_tx,
             globals.clone(),
-            beacon_processor_tx,
+            BeaconProcessorSend(beacon_processor_tx),
             chain,
             log.new(o!("component" => "network_context")),
         );
diff --git a/beacon_node/src/cli.rs b/beacon_node/src/cli.rs
index 41f033607..8c8ec666d 100644
--- a/beacon_node/src/cli.rs
+++ b/beacon_node/src/cli.rs
@@ -1,5 +1,6 @@
 use clap::{App, Arg};
 use strum::VariantNames;
+use types::ProgressiveBalancesMode;
 
 pub fn cli_app<'a, 'b>() -> App<'a, 'b> {
     App::new("beacon_node")
@@ -1159,4 +1160,17 @@ pub fn cli_app<'a, 'b>() -> App<'a, 'b> {
                     developers. This directory is not pruned, users should be careful to avoid \
                     filling up their disks.")
         )
+        .arg(
+            Arg::with_name("progressive-balances")
+                .long("progressive-balances")
+                .value_name("MODE")
+                .help("Options to enable or disable the progressive balances cache for \
+                        unrealized FFG progression calculation. The default `checked` mode compares \
+                        the progressive balances from the cache against results from the existing \
+                        method. If there is a mismatch, it falls back to the existing method. The \
+                        optimized mode (`fast`) is faster but is still experimental, and is \
+                        not recommended for mainnet usage at this time.")
+                .takes_value(true)
+                .possible_values(ProgressiveBalancesMode::VARIANTS)
+        )
 }
diff --git a/beacon_node/src/config.rs b/beacon_node/src/config.rs
index b15536031..8d2cb3822 100644
--- a/beacon_node/src/config.rs
+++ b/beacon_node/src/config.rs
@@ -837,6 +837,12 @@ pub fn get_config<E: EthSpec>(
         client_config.network.invalid_block_storage = Some(path);
     }
 
+    if let Some(progressive_balances_mode) =
+        clap_utils::parse_optional(cli_args, "progressive-balances")?
+    {
+        client_config.chain.progressive_balances_mode = progressive_balances_mode;
+    }
+
     Ok(client_config)
 }
 
diff --git a/beacon_node/store/src/partial_beacon_state.rs b/beacon_node/store/src/partial_beacon_state.rs
index 5f864c44a..1fb5751a0 100644
--- a/beacon_node/store/src/partial_beacon_state.rs
+++ b/beacon_node/store/src/partial_beacon_state.rs
@@ -395,6 +395,7 @@ macro_rules! impl_try_into_beacon_state {
 
             // Caching
             total_active_balance: <_>::default(),
+            progressive_balances_cache: <_>::default(),
             committee_caches: <_>::default(),
             pubkey_cache: <_>::default(),
             exit_cache: <_>::default(),
diff --git a/beacon_node/store/src/reconstruct.rs b/beacon_node/store/src/reconstruct.rs
index cd50babdb..bac5d3cc8 100644
--- a/beacon_node/store/src/reconstruct.rs
+++ b/beacon_node/store/src/reconstruct.rs
@@ -63,7 +63,7 @@ where
             .load_cold_state_by_slot(lower_limit_slot)?
             .ok_or(HotColdDBError::MissingLowerLimitState(lower_limit_slot))?;
 
-        state.build_all_caches(&self.spec)?;
+        state.build_caches(&self.spec)?;
 
         process_results(block_root_iter, |iter| -> Result<(), Error> {
             let mut io_batch = vec![];
diff --git a/boot_node/Cargo.toml b/boot_node/Cargo.toml
index 5c2dc9b4f..c3dd3bd19 100644
--- a/boot_node/Cargo.toml
+++ b/boot_node/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "boot_node"
-version = "4.2.0"
+version = "4.3.0"
 authors = ["Sigma Prime <contact@sigmaprime.io>"]
 edition = "2021"
 
diff --git a/common/eth2/src/lib.rs b/common/eth2/src/lib.rs
index 32d1bc2be..ba5f6016b 100644
--- a/common/eth2/src/lib.rs
+++ b/common/eth2/src/lib.rs
@@ -322,6 +322,26 @@ impl BeaconNodeHttpClient {
         ok_or_error(response).await
     }
 
+    /// Generic POST function supporting arbitrary responses and timeouts.
+    async fn post_generic_with_consensus_version<T: Serialize, U: IntoUrl>(
+        &self,
+        url: U,
+        body: &T,
+        timeout: Option<Duration>,
+        fork: ForkName,
+    ) -> Result<Response, Error> {
+        let mut builder = self.client.post(url);
+        if let Some(timeout) = timeout {
+            builder = builder.timeout(timeout);
+        }
+        let response = builder
+            .header(CONSENSUS_VERSION_HEADER, fork.to_string())
+            .json(body)
+            .send()
+            .await?;
+        ok_or_error(response).await
+    }
+
     /// `GET beacon/genesis`
     ///
     /// ## Errors
@@ -654,6 +674,76 @@ impl BeaconNodeHttpClient {
         Ok(())
     }
 
+    pub fn post_beacon_blocks_v2_path(
+        &self,
+        validation_level: Option<BroadcastValidation>,
+    ) -> Result<Url, Error> {
+        let mut path = self.eth_path(V2)?;
+        path.path_segments_mut()
+            .map_err(|_| Error::InvalidUrl(self.server.clone()))?
+            .extend(&["beacon", "blocks"]);
+
+        path.set_query(
+            validation_level
+                .map(|v| format!("broadcast_validation={}", v))
+                .as_deref(),
+        );
+
+        Ok(path)
+    }
+
+    pub fn post_beacon_blinded_blocks_v2_path(
+        &self,
+        validation_level: Option<BroadcastValidation>,
+    ) -> Result<Url, Error> {
+        let mut path = self.eth_path(V2)?;
+        path.path_segments_mut()
+            .map_err(|_| Error::InvalidUrl(self.server.clone()))?
+            .extend(&["beacon", "blinded_blocks"]);
+
+        path.set_query(
+            validation_level
+                .map(|v| format!("broadcast_validation={}", v))
+                .as_deref(),
+        );
+
+        Ok(path)
+    }
+
+    /// `POST v2/beacon/blocks`
+    pub async fn post_beacon_blocks_v2<T: EthSpec, Payload: AbstractExecPayload<T>>(
+        &self,
+        block: &SignedBeaconBlock<T, Payload>,
+        validation_level: Option<BroadcastValidation>,
+    ) -> Result<(), Error> {
+        self.post_generic_with_consensus_version(
+            self.post_beacon_blocks_v2_path(validation_level)?,
+            block,
+            Some(self.timeouts.proposal),
+            block.message().body().fork_name(),
+        )
+        .await?;
+
+        Ok(())
+    }
+
+    /// `POST v2/beacon/blinded_blocks`
+    pub async fn post_beacon_blinded_blocks_v2<T: EthSpec>(
+        &self,
+        block: &SignedBlindedBeaconBlock<T>,
+        validation_level: Option<BroadcastValidation>,
+    ) -> Result<(), Error> {
+        self.post_generic_with_consensus_version(
+            self.post_beacon_blinded_blocks_v2_path(validation_level)?,
+            block,
+            Some(self.timeouts.proposal),
+            block.message().body().fork_name(),
+        )
+        .await?;
+
+        Ok(())
+    }
+
     /// Path for `v2/beacon/blocks`
     pub fn get_beacon_blocks_path(&self, block_id: BlockId) -> Result<Url, Error> {
         let mut path = self.eth_path(V2)?;
diff --git a/common/eth2/src/types.rs b/common/eth2/src/types.rs
index 6e22f1b0c..b7fc67304 100644
--- a/common/eth2/src/types.rs
+++ b/common/eth2/src/types.rs
@@ -7,7 +7,7 @@ use mediatype::{names, MediaType, MediaTypeList};
 use serde::{Deserialize, Serialize};
 use ssz_derive::Encode;
 use std::convert::TryFrom;
-use std::fmt;
+use std::fmt::{self, Display};
 use std::str::{from_utf8, FromStr};
 use std::time::Duration;
 pub use types::*;
@@ -1261,6 +1261,50 @@ pub struct ForkChoiceNode {
     pub execution_block_hash: Option<Hash256>,
 }
 
+#[derive(Copy, Clone, Debug, Serialize, Deserialize, PartialEq, Eq)]
+#[serde(rename_all = "snake_case")]
+pub enum BroadcastValidation {
+    Gossip,
+    Consensus,
+    ConsensusAndEquivocation,
+}
+
+impl Default for BroadcastValidation {
+    fn default() -> Self {
+        Self::Gossip
+    }
+}
+
+impl Display for BroadcastValidation {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Gossip => write!(f, "gossip"),
+            Self::Consensus => write!(f, "consensus"),
+            Self::ConsensusAndEquivocation => write!(f, "consensus_and_equivocation"),
+        }
+    }
+}
+
+impl FromStr for BroadcastValidation {
+    type Err = &'static str;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s {
+            "gossip" => Ok(Self::Gossip),
+            "consensus" => Ok(Self::Consensus),
+            "consensus_and_equivocation" => Ok(Self::ConsensusAndEquivocation),
+            _ => Err("Invalid broadcast validation level"),
+        }
+    }
+}
+
+#[derive(Default, Deserialize, Serialize)]
+#[serde(rename_all = "snake_case")]
+pub struct BroadcastValidationQuery {
+    #[serde(default)]
+    pub broadcast_validation: BroadcastValidation,
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
diff --git a/common/eth2_network_config/built_in_network_configs/mainnet/boot_enr.yaml b/common/eth2_network_config/built_in_network_configs/mainnet/boot_enr.yaml
index 196629cb8..428a082cc 100644
--- a/common/eth2_network_config/built_in_network_configs/mainnet/boot_enr.yaml
+++ b/common/eth2_network_config/built_in_network_configs/mainnet/boot_enr.yaml
@@ -1,6 +1,8 @@
 # Lighthouse Team (Sigma Prime)
-- enr:-Jq4QItoFUuug_n_qbYbU0OY04-np2wT8rUCauOOXNi0H3BWbDj-zbfZb7otA7jZ6flbBpx1LNZK2TDebZ9dEKx84LYBhGV0aDKQtTA_KgEAAAD__________4JpZIJ2NIJpcISsaa0ZiXNlY3AyNTZrMaEDHAD2JKYevx89W0CcFJFiskdcEzkH_Wdv9iW42qLK79ODdWRwgiMo
-- enr:-Jq4QN_YBsUOqQsty1OGvYv48PMaiEt1AzGD1NkYQHaxZoTyVGqMYXg0K9c0LPNWC9pkXmggApp8nygYLsQwScwAgfgBhGV0aDKQtTA_KgEAAAD__________4JpZIJ2NIJpcISLosQxiXNlY3AyNTZrMaEDBJj7_dLFACaxBfaI8KZTh_SSJUjhyAyfshimvSqo22WDdWRwgiMo
+- enr:-Le4QPUXJS2BTORXxyx2Ia-9ae4YqA_JWX3ssj4E_J-3z1A-HmFGrU8BpvpqhNabayXeOZ2Nq_sbeDgtzMJpLLnXFgAChGV0aDKQtTA_KgEAAAAAIgEAAAAAAIJpZIJ2NIJpcISsaa0Zg2lwNpAkAIkHAAAAAPA8kv_-awoTiXNlY3AyNTZrMaEDHAD2JKYevx89W0CcFJFiskdcEzkH_Wdv9iW42qLK79ODdWRwgiMohHVkcDaCI4I
+- enr:-Le4QLHZDSvkLfqgEo8IWGG96h6mxwe_PsggC20CL3neLBjfXLGAQFOPSltZ7oP6ol54OvaNqO02Rnvb8YmDR274uq8ChGV0aDKQtTA_KgEAAAAAIgEAAAAAAIJpZIJ2NIJpcISLosQxg2lwNpAqAX4AAAAAAPA8kv_-ax65iXNlY3AyNTZrMaEDBJj7_dLFACaxBfaI8KZTh_SSJUjhyAyfshimvSqo22WDdWRwgiMohHVkcDaCI4I
+- enr:-Le4QH6LQrusDbAHPjU_HcKOuMeXfdEB5NJyXgHWFadfHgiySqeDyusQMvfphdYWOzuSZO9Uq2AMRJR5O4ip7OvVma8BhGV0aDKQtTA_KgEAAAAAIgEAAAAAAIJpZIJ2NIJpcISLY9ncg2lwNpAkAh8AgQIBAAAAAAAAAAmXiXNlY3AyNTZrMaECDYCZTZEksF-kmgPholqgVt8IXr-8L7Nu7YrZ7HUpgxmDdWRwgiMohHVkcDaCI4I
+- enr:-Le4QIqLuWybHNONr933Lk0dcMmAB5WgvGKRyDihy1wHDIVlNuuztX62W51voT4I8qD34GcTEOTmag1bcdZ_8aaT4NUBhGV0aDKQtTA_KgEAAAAAIgEAAAAAAIJpZIJ2NIJpcISLY04ng2lwNpAkAh8AgAIBAAAAAAAAAA-fiXNlY3AyNTZrMaEDscnRV6n1m-D9ID5UsURk0jsoKNXt1TIrj8uKOGW6iluDdWRwgiMohHVkcDaCI4I
 # EF Team
 - enr:-Ku4QHqVeJ8PPICcWk1vSn_XcSkjOkNiTg6Fmii5j6vUQgvzMc9L1goFnLKgXqBJspJjIsB91LTOleFmyWWrFVATGngBh2F0dG5ldHOIAAAAAAAAAACEZXRoMpC1MD8qAAAAAP__________gmlkgnY0gmlwhAMRHkWJc2VjcDI1NmsxoQKLVXFOhp2uX6jeT0DvvDpPcU8FWMjQdR4wMuORMhpX24N1ZHCCIyg
 - enr:-Ku4QG-2_Md3sZIAUebGYT6g0SMskIml77l6yR-M_JXc-UdNHCmHQeOiMLbylPejyJsdAPsTHJyjJB2sYGDLe0dn8uYBh2F0dG5ldHOIAAAAAAAAAACEZXRoMpC1MD8qAAAAAP__________gmlkgnY0gmlwhBLY-NyJc2VjcDI1NmsxoQORcM6e19T1T9gi7jxEZjk_sjVLGFscUNqAY9obgZaxbIN1ZHCCIyg
@@ -15,4 +17,4 @@
 - enr:-Ku4QPp9z1W4tAO8Ber_NQierYaOStqhDqQdOPY3bB3jDgkjcbk6YrEnVYIiCBbTxuar3CzS528d2iE7TdJsrL-dEKoBh2F0dG5ldHOIAAAAAAAAAACEZXRoMpD1pf1CAAAAAP__________gmlkgnY0gmlwhBLf22SJc2VjcDI1NmsxoQMw5fqqkw2hHC4F5HZZDPsNmPdB1Gi8JPQK7pRc9XHh-oN1ZHCCKvg
 # Nimbus team
 - enr:-LK4QA8FfhaAjlb_BXsXxSfiysR7R52Nhi9JBt4F8SPssu8hdE1BXQQEtVDC3qStCW60LSO7hEsVHv5zm8_6Vnjhcn0Bh2F0dG5ldHOIAAAAAAAAAACEZXRoMpC1MD8qAAAAAP__________gmlkgnY0gmlwhAN4aBKJc2VjcDI1NmsxoQJerDhsJ-KxZ8sHySMOCmTO6sHM3iCFQ6VMvLTe948MyYN0Y3CCI4yDdWRwgiOM
-- enr:-LK4QKWrXTpV9T78hNG6s8AM6IO4XH9kFT91uZtFg1GcsJ6dKovDOr1jtAAFPnS2lvNltkOGA9k29BUN7lFh_sjuc9QBh2F0dG5ldHOIAAAAAAAAAACEZXRoMpC1MD8qAAAAAP__________gmlkgnY0gmlwhANAdd-Jc2VjcDI1NmsxoQLQa6ai7y9PMN5hpLe5HmiJSlYzMuzP7ZhwRiwHvqNXdoN0Y3CCI4yDdWRwgiOM
+- enr:-LK4QKWrXTpV9T78hNG6s8AM6IO4XH9kFT91uZtFg1GcsJ6dKovDOr1jtAAFPnS2lvNltkOGA9k29BUN7lFh_sjuc9QBh2F0dG5ldHOIAAAAAAAAAACEZXRoMpC1MD8qAAAAAP__________gmlkgnY0gmlwhANAdd-Jc2VjcDI1NmsxoQLQa6ai7y9PMN5hpLe5HmiJSlYzMuzP7ZhwRiwHvqNXdoN0Y3CCI4yDdWRwgiOM
\ No newline at end of file
diff --git a/common/lighthouse_version/src/lib.rs b/common/lighthouse_version/src/lib.rs
index 3f2745bf9..e874432fb 100644
--- a/common/lighthouse_version/src/lib.rs
+++ b/common/lighthouse_version/src/lib.rs
@@ -17,8 +17,8 @@ pub const VERSION: &str = git_version!(
         // NOTE: using --match instead of --exclude for compatibility with old Git
         "--match=thiswillnevermatchlol"
     ],
-    prefix = "Lighthouse/v4.2.0-",
-    fallback = "Lighthouse/v4.2.0"
+    prefix = "Lighthouse/v4.3.0-",
+    fallback = "Lighthouse/v4.3.0"
 );
 
 /// Returns `VERSION`, but with platform information appended to the end.
diff --git a/consensus/fork_choice/src/fork_choice.rs b/consensus/fork_choice/src/fork_choice.rs
index 1026f996f..8ed312923 100644
--- a/consensus/fork_choice/src/fork_choice.rs
+++ b/consensus/fork_choice/src/fork_choice.rs
@@ -1,10 +1,15 @@
 use crate::{ForkChoiceStore, InvalidationOperation};
+use per_epoch_processing::altair::participation_cache::Error as ParticipationCacheError;
 use proto_array::{
     Block as ProtoBlock, DisallowedReOrgOffsets, ExecutionStatus, ProposerHeadError,
     ProposerHeadInfo, ProtoArrayForkChoice, ReOrgThreshold,
 };
-use slog::{crit, debug, warn, Logger};
+use slog::{crit, debug, error, warn, Logger};
 use ssz_derive::{Decode, Encode};
+use state_processing::per_epoch_processing::altair::ParticipationCache;
+use state_processing::per_epoch_processing::{
+    weigh_justification_and_finalization, JustificationAndFinalizationState,
+};
 use state_processing::{
     per_block_processing::errors::AttesterSlashingValidationError, per_epoch_processing,
 };
@@ -18,6 +23,7 @@ use types::{
     EthSpec, ExecPayload, ExecutionBlockHash, Hash256, IndexedAttestation, RelativeEpoch,
     SignedBeaconBlock, Slot,
 };
+use types::{ProgressiveBalancesCache, ProgressiveBalancesMode};
 
 #[derive(Debug)]
 pub enum Error<T> {
@@ -72,7 +78,9 @@ pub enum Error<T> {
     },
     UnrealizedVoteProcessing(state_processing::EpochProcessingError),
     ParticipationCacheBuild(BeaconStateError),
+    ParticipationCacheError(ParticipationCacheError),
     ValidatorStatuses(BeaconStateError),
+    ProgressiveBalancesCacheCheckFailed(String),
 }
 
 impl<T> From<InvalidAttestation> for Error<T> {
@@ -93,6 +101,18 @@ impl<T> From<state_processing::EpochProcessingError> for Error<T> {
     }
 }
 
+impl<T> From<BeaconStateError> for Error<T> {
+    fn from(e: BeaconStateError) -> Self {
+        Error::BeaconStateError(e)
+    }
+}
+
+impl<T> From<ParticipationCacheError> for Error<T> {
+    fn from(e: ParticipationCacheError) -> Self {
+        Error::ParticipationCacheError(e)
+    }
+}
+
 #[derive(Debug, Clone, Copy)]
 /// Controls how fork choice should behave when restoring from a persisted fork choice.
 pub enum ResetPayloadStatuses {
@@ -645,7 +665,9 @@ where
         block_delay: Duration,
         state: &BeaconState<E>,
         payload_verification_status: PayloadVerificationStatus,
+        progressive_balances_mode: ProgressiveBalancesMode,
         spec: &ChainSpec,
+        log: &Logger,
     ) -> Result<(), Error<T::Error>> {
         // If this block has already been processed we do not need to reprocess it.
         // We check this immediately in case re-processing the block mutates some property of the
@@ -739,46 +761,84 @@ where
                 parent_justified.epoch == block_epoch && parent_finalized.epoch + 1 >= block_epoch
             });
 
-        let (unrealized_justified_checkpoint, unrealized_finalized_checkpoint) =
-            if let Some((parent_justified, parent_finalized)) = parent_checkpoints {
-                (parent_justified, parent_finalized)
-            } else {
-                let justification_and_finalization_state = match block {
-                    // TODO(deneb): Ensure that the final specification
-                    // does not substantially modify per epoch processing.
-                    BeaconBlockRef::Deneb(_)
-                    | BeaconBlockRef::Capella(_)
-                    | BeaconBlockRef::Merge(_)
-                    | BeaconBlockRef::Altair(_) => {
-                        let participation_cache =
-                            per_epoch_processing::altair::ParticipationCache::new(state, spec)
-                                .map_err(Error::ParticipationCacheBuild)?;
+        let (unrealized_justified_checkpoint, unrealized_finalized_checkpoint) = if let Some((
+            parent_justified,
+            parent_finalized,
+        )) =
+            parent_checkpoints
+        {
+            (parent_justified, parent_finalized)
+        } else {
+            let justification_and_finalization_state = match block {
+               BeaconBlockRef::Deneb(_)| BeaconBlockRef::Capella(_)
+                | BeaconBlockRef::Merge(_)
+                | BeaconBlockRef::Altair(_) => match progressive_balances_mode {
+                    ProgressiveBalancesMode::Disabled => {
+                        let participation_cache = ParticipationCache::new(state, spec)
+                            .map_err(Error::ParticipationCacheBuild)?;
                         per_epoch_processing::altair::process_justification_and_finalization(
                             state,
                             &participation_cache,
                         )?
                     }
-                    BeaconBlockRef::Base(_) => {
-                        let mut validator_statuses =
-                            per_epoch_processing::base::ValidatorStatuses::new(state, spec)
-                                .map_err(Error::ValidatorStatuses)?;
-                        validator_statuses
-                            .process_attestations(state)
-                            .map_err(Error::ValidatorStatuses)?;
-                        per_epoch_processing::base::process_justification_and_finalization(
-                            state,
-                            &validator_statuses.total_balances,
-                            spec,
-                        )?
-                    }
-                };
+                    ProgressiveBalancesMode::Fast
+                    | ProgressiveBalancesMode::Checked
+                    | ProgressiveBalancesMode::Strict => {
+                        let maybe_participation_cache = progressive_balances_mode
+                            .perform_comparative_checks()
+                            .then(|| {
+                                ParticipationCache::new(state, spec)
+                                    .map_err(Error::ParticipationCacheBuild)
+                            })
+                            .transpose()?;
 
-                (
-                    justification_and_finalization_state.current_justified_checkpoint(),
-                    justification_and_finalization_state.finalized_checkpoint(),
-                )
+                        process_justification_and_finalization_from_progressive_cache::<E, T>(
+                                state,
+                                maybe_participation_cache.as_ref(),
+                            )
+                            .or_else(|e| {
+                                if progressive_balances_mode != ProgressiveBalancesMode::Strict {
+                                    error!(
+                                        log,
+                                        "Processing with progressive balances cache failed";
+                                        "info" => "falling back to the non-optimized processing method",
+                                        "error" => ?e,
+                                    );
+                                    let participation_cache = maybe_participation_cache
+                                        .map(Ok)
+                                        .unwrap_or_else(|| ParticipationCache::new(state, spec))
+                                        .map_err(Error::ParticipationCacheBuild)?;
+                                    per_epoch_processing::altair::process_justification_and_finalization(
+                                        state,
+                                        &participation_cache,
+                                    ).map_err(Error::from)
+                                } else {
+                                    Err(e)
+                                }
+                            })?
+                    }
+                },
+                BeaconBlockRef::Base(_) => {
+                    let mut validator_statuses =
+                        per_epoch_processing::base::ValidatorStatuses::new(state, spec)
+                            .map_err(Error::ValidatorStatuses)?;
+                    validator_statuses
+                        .process_attestations(state)
+                        .map_err(Error::ValidatorStatuses)?;
+                    per_epoch_processing::base::process_justification_and_finalization(
+                        state,
+                        &validator_statuses.total_balances,
+                        spec,
+                    )?
+                }
             };
 
+            (
+                justification_and_finalization_state.current_justified_checkpoint(),
+                justification_and_finalization_state.finalized_checkpoint(),
+            )
+        };
+
         // Update best known unrealized justified & finalized checkpoints
         if unrealized_justified_checkpoint.epoch
             > self.fc_store.unrealized_justified_checkpoint().epoch
@@ -1504,6 +1564,92 @@ where
     }
 }
 
+/// Process justification and finalization using progressive cache. Also performs a comparative
+/// check against the `ParticipationCache` if it is supplied.
+///
+/// Returns an error if the cache is not initialized or if there is a mismatch on the comparative check.
+fn process_justification_and_finalization_from_progressive_cache<E, T>(
+    state: &BeaconState<E>,
+    maybe_participation_cache: Option<&ParticipationCache>,
+) -> Result<JustificationAndFinalizationState<E>, Error<T::Error>>
+where
+    E: EthSpec,
+    T: ForkChoiceStore<E>,
+{
+    let justification_and_finalization_state = JustificationAndFinalizationState::new(state);
+    if state.current_epoch() <= E::genesis_epoch() + 1 {
+        return Ok(justification_and_finalization_state);
+    }
+
+    // Load cached balances
+    let progressive_balances_cache: &ProgressiveBalancesCache = state.progressive_balances_cache();
+    let previous_target_balance =
+        progressive_balances_cache.previous_epoch_target_attesting_balance()?;
+    let current_target_balance =
+        progressive_balances_cache.current_epoch_target_attesting_balance()?;
+    let total_active_balance = state.get_total_active_balance()?;
+
+    if let Some(participation_cache) = maybe_participation_cache {
+        check_progressive_balances::<E, T>(
+            state,
+            participation_cache,
+            previous_target_balance,
+            current_target_balance,
+            total_active_balance,
+        )?;
+    }
+
+    weigh_justification_and_finalization(
+        justification_and_finalization_state,
+        total_active_balance,
+        previous_target_balance,
+        current_target_balance,
+    )
+    .map_err(Error::from)
+}
+
+/// Perform comparative checks against `ParticipationCache`, will return error if there's a mismatch.
+fn check_progressive_balances<E, T>(
+    state: &BeaconState<E>,
+    participation_cache: &ParticipationCache,
+    cached_previous_target_balance: u64,
+    cached_current_target_balance: u64,
+    cached_total_active_balance: u64,
+) -> Result<(), Error<T::Error>>
+where
+    E: EthSpec,
+    T: ForkChoiceStore<E>,
+{
+    let slot = state.slot();
+    let epoch = state.current_epoch();
+
+    // Check previous epoch target balances
+    let previous_target_balance = participation_cache.previous_epoch_target_attesting_balance()?;
+    if previous_target_balance != cached_previous_target_balance {
+        return Err(Error::ProgressiveBalancesCacheCheckFailed(
+            format!("Previous epoch target attesting balance mismatch, slot: {}, epoch: {}, actual: {}, cached: {}", slot, epoch, previous_target_balance, cached_previous_target_balance)
+        ));
+    }
+
+    // Check current epoch target balances
+    let current_target_balance = participation_cache.current_epoch_target_attesting_balance()?;
+    if current_target_balance != cached_current_target_balance {
+        return Err(Error::ProgressiveBalancesCacheCheckFailed(
+            format!("Current epoch target attesting balance mismatch, slot: {}, epoch: {}, actual: {}, cached: {}", slot, epoch, current_target_balance, cached_current_target_balance)
+        ));
+    }
+
+    // Check current epoch total balances
+    let total_active_balance = participation_cache.current_epoch_total_active_balance();
+    if total_active_balance != cached_total_active_balance {
+        return Err(Error::ProgressiveBalancesCacheCheckFailed(
+            format!("Current epoch total active balance mismatch, slot: {}, epoch: {}, actual: {}, cached: {}", slot, epoch, total_active_balance, cached_total_active_balance)
+        ));
+    }
+
+    Ok(())
+}
+
 /// Helper struct that is used to encode/decode the state of the `ForkChoice` as SSZ bytes.
 ///
 /// This is used when persisting the state of the fork choice to disk.
diff --git a/consensus/fork_choice/tests/tests.rs b/consensus/fork_choice/tests/tests.rs
index 9062cb550..06fad8727 100644
--- a/consensus/fork_choice/tests/tests.rs
+++ b/consensus/fork_choice/tests/tests.rs
@@ -17,12 +17,13 @@ use fork_choice::{
 use store::MemoryStore;
 use types::{
     test_utils::generate_deterministic_keypair, BeaconBlockRef, BeaconState, ChainSpec, Checkpoint,
-    Epoch, EthSpec, Hash256, IndexedAttestation, MainnetEthSpec, SignedBeaconBlock, Slot, SubnetId,
+    Epoch, EthSpec, ForkName, Hash256, IndexedAttestation, MainnetEthSpec, ProgressiveBalancesMode,
+    RelativeEpoch, SignedBeaconBlock, Slot, SubnetId,
 };
 
 pub type E = MainnetEthSpec;
 
-pub const VALIDATOR_COUNT: usize = 32;
+pub const VALIDATOR_COUNT: usize = 64;
 
 /// Defines some delay between when an attestation is created and when it is mutated.
 pub enum MutationDelay {
@@ -68,6 +69,24 @@ impl ForkChoiceTest {
         Self { harness }
     }
 
+    /// Creates a new tester with the specified `ProgressiveBalancesMode` and genesis from latest fork.
+    fn new_with_progressive_balances_mode(mode: ProgressiveBalancesMode) -> ForkChoiceTest {
+        // genesis with latest fork (at least altair required to test the cache)
+        let spec = ForkName::latest().make_genesis_spec(ChainSpec::default());
+        let harness = BeaconChainHarness::builder(MainnetEthSpec)
+            .spec(spec)
+            .chain_config(ChainConfig {
+                progressive_balances_mode: mode,
+                ..ChainConfig::default()
+            })
+            .deterministic_keypairs(VALIDATOR_COUNT)
+            .fresh_ephemeral_store()
+            .mock_execution_layer()
+            .build();
+
+        Self { harness }
+    }
+
     /// Get a value from the `ForkChoice` instantiation.
     fn get<T, U>(&self, func: T) -> U
     where
@@ -212,6 +231,39 @@ impl ForkChoiceTest {
         self
     }
 
+    /// Slash a validator from the previous epoch committee.
+    pub async fn add_previous_epoch_attester_slashing(self) -> Self {
+        let state = self.harness.get_current_state();
+        let previous_epoch_shuffling = state.get_shuffling(RelativeEpoch::Previous).unwrap();
+        let validator_indices = previous_epoch_shuffling
+            .iter()
+            .map(|idx| *idx as u64)
+            .take(1)
+            .collect();
+
+        self.harness
+            .add_attester_slashing(validator_indices)
+            .unwrap();
+
+        self
+    }
+
+    /// Slash the proposer of a block in the previous epoch.
+    pub async fn add_previous_epoch_proposer_slashing(self, slots_per_epoch: u64) -> Self {
+        let previous_epoch_slot = self.harness.get_current_slot() - slots_per_epoch;
+        let previous_epoch_block = self
+            .harness
+            .chain
+            .block_at_slot(previous_epoch_slot, WhenSlotSkipped::None)
+            .unwrap()
+            .unwrap();
+        let proposer_index: u64 = previous_epoch_block.message().proposer_index();
+
+        self.harness.add_proposer_slashing(proposer_index).unwrap();
+
+        self
+    }
+
     /// Apply `count` blocks to the chain (without attestations).
     pub async fn apply_blocks_without_new_attestations(self, count: usize) -> Self {
         self.harness.advance_slot();
@@ -286,7 +338,9 @@ impl ForkChoiceTest {
                 Duration::from_secs(0),
                 &state,
                 PayloadVerificationStatus::Verified,
+                self.harness.chain.config.progressive_balances_mode,
                 &self.harness.chain.spec,
+                self.harness.logger(),
             )
             .unwrap();
         self
@@ -328,7 +382,9 @@ impl ForkChoiceTest {
                 Duration::from_secs(0),
                 &state,
                 PayloadVerificationStatus::Verified,
+                self.harness.chain.config.progressive_balances_mode,
                 &self.harness.chain.spec,
+                self.harness.logger(),
             )
             .err()
             .expect("on_block did not return an error");
@@ -1287,3 +1343,49 @@ async fn weak_subjectivity_check_epoch_boundary_is_skip_slot_failure() {
         .assert_finalized_epoch_is_less_than(checkpoint.epoch)
         .assert_shutdown_signal_sent();
 }
+
+/// Checks that `ProgressiveBalancesCache` is updated correctly after an attester slashing event,
+/// where the slashed validator is a target attester in previous / current epoch.
+#[tokio::test]
+async fn progressive_balances_cache_attester_slashing() {
+    ForkChoiceTest::new_with_progressive_balances_mode(ProgressiveBalancesMode::Strict)
+        // first two epochs
+        .apply_blocks_while(|_, state| state.finalized_checkpoint().epoch == 0)
+        .await
+        .unwrap()
+        .add_previous_epoch_attester_slashing()
+        .await
+        // expect fork choice to import blocks successfully after a previous epoch attester is
+        // slashed, i.e. the slashed attester's balance is correctly excluded from
+        // the previous epoch total balance in `ProgressiveBalancesCache`.
+        .apply_blocks(1)
+        .await
+        // expect fork choice to import another epoch of blocks successfully - the slashed
+        // attester's balance should be excluded from the current epoch total balance in
+        // `ProgressiveBalancesCache` as well.
+        .apply_blocks(MainnetEthSpec::slots_per_epoch() as usize)
+        .await;
+}
+
+/// Checks that `ProgressiveBalancesCache` is updated correctly after a proposer slashing event,
+/// where the slashed validator is a target attester in previous / current epoch.
+#[tokio::test]
+async fn progressive_balances_cache_proposer_slashing() {
+    ForkChoiceTest::new_with_progressive_balances_mode(ProgressiveBalancesMode::Strict)
+        // first two epochs
+        .apply_blocks_while(|_, state| state.finalized_checkpoint().epoch == 0)
+        .await
+        .unwrap()
+        .add_previous_epoch_proposer_slashing(MainnetEthSpec::slots_per_epoch())
+        .await
+        // expect fork choice to import blocks successfully after a previous epoch proposer is
+        // slashed, i.e. the slashed proposer's balance is correctly excluded from
+        // the previous epoch total balance in `ProgressiveBalancesCache`.
+        .apply_blocks(1)
+        .await
+        // expect fork choice to import another epoch of blocks successfully - the slashed
+        // proposer's balance should be excluded from the current epoch total balance in
+        // `ProgressiveBalancesCache` as well.
+        .apply_blocks(MainnetEthSpec::slots_per_epoch() as usize)
+        .await;
+}
diff --git a/consensus/state_processing/src/common/mod.rs b/consensus/state_processing/src/common/mod.rs
index 8a2e2439b..ffe8be3a0 100644
--- a/consensus/state_processing/src/common/mod.rs
+++ b/consensus/state_processing/src/common/mod.rs
@@ -7,6 +7,7 @@ mod slash_validator;
 
 pub mod altair;
 pub mod base;
+pub mod update_progressive_balances_cache;
 
 pub use deposit_data_tree::DepositDataTree;
 pub use get_attestation_participation::get_attestation_participation_flag_indices;
diff --git a/consensus/state_processing/src/common/slash_validator.rs b/consensus/state_processing/src/common/slash_validator.rs
index 94148ff6c..d8b1c1a10 100644
--- a/consensus/state_processing/src/common/slash_validator.rs
+++ b/consensus/state_processing/src/common/slash_validator.rs
@@ -1,3 +1,4 @@
+use crate::common::update_progressive_balances_cache::update_progressive_balances_on_slashing;
 use crate::{
     common::{decrease_balance, increase_balance, initiate_validator_exit},
     per_block_processing::errors::BlockProcessingError,
@@ -43,6 +44,8 @@ pub fn slash_validator<T: EthSpec>(
             .safe_div(spec.min_slashing_penalty_quotient_for_state(state))?,
     )?;
 
+    update_progressive_balances_on_slashing(state, slashed_index)?;
+
     // Apply proposer and whistleblower rewards
     let proposer_index = ctxt.get_proposer_index(state, spec)? as usize;
     let whistleblower_index = opt_whistleblower_index.unwrap_or(proposer_index);
diff --git a/consensus/state_processing/src/common/update_progressive_balances_cache.rs b/consensus/state_processing/src/common/update_progressive_balances_cache.rs
new file mode 100644
index 000000000..45b5d657a
--- /dev/null
+++ b/consensus/state_processing/src/common/update_progressive_balances_cache.rs
@@ -0,0 +1,142 @@
+/// A collection of all functions that mutates the `ProgressiveBalancesCache`.
+use crate::metrics::{
+    PARTICIPATION_CURR_EPOCH_TARGET_ATTESTING_GWEI_PROGRESSIVE_TOTAL,
+    PARTICIPATION_PREV_EPOCH_TARGET_ATTESTING_GWEI_PROGRESSIVE_TOTAL,
+};
+use crate::per_epoch_processing::altair::ParticipationCache;
+use crate::{BlockProcessingError, EpochProcessingError};
+use lighthouse_metrics::set_gauge;
+use ssz_types::VariableList;
+use std::borrow::Cow;
+use types::consts::altair::TIMELY_TARGET_FLAG_INDEX;
+use types::{
+    is_progressive_balances_enabled, BeaconState, BeaconStateError, ChainSpec, Epoch, EthSpec,
+    ParticipationFlags, ProgressiveBalancesCache,
+};
+
+/// Initializes the `ProgressiveBalancesCache` cache using balance values from the
+/// `ParticipationCache`. If the optional `&ParticipationCache` is not supplied, it will be computed
+/// from the `BeaconState`.
+pub fn initialize_progressive_balances_cache<E: EthSpec>(
+    state: &mut BeaconState<E>,
+    maybe_participation_cache: Option<&ParticipationCache>,
+    spec: &ChainSpec,
+) -> Result<(), BeaconStateError> {
+    if !is_progressive_balances_enabled(state)
+        || state.progressive_balances_cache().is_initialized()
+    {
+        return Ok(());
+    }
+
+    let participation_cache = match maybe_participation_cache {
+        Some(cache) => Cow::Borrowed(cache),
+        None => Cow::Owned(ParticipationCache::new(state, spec)?),
+    };
+
+    let previous_epoch_target_attesting_balance = participation_cache
+        .previous_epoch_target_attesting_balance_raw()
+        .map_err(|e| BeaconStateError::ParticipationCacheError(format!("{e:?}")))?;
+
+    let current_epoch_target_attesting_balance = participation_cache
+        .current_epoch_target_attesting_balance_raw()
+        .map_err(|e| BeaconStateError::ParticipationCacheError(format!("{e:?}")))?;
+
+    let current_epoch = state.current_epoch();
+    state.progressive_balances_cache_mut().initialize(
+        current_epoch,
+        previous_epoch_target_attesting_balance,
+        current_epoch_target_attesting_balance,
+    );
+
+    update_progressive_balances_metrics(state.progressive_balances_cache())?;
+
+    Ok(())
+}
+
+/// Updates the `ProgressiveBalancesCache` when a new target attestation has been processed.
+pub fn update_progressive_balances_on_attestation<T: EthSpec>(
+    state: &mut BeaconState<T>,
+    epoch: Epoch,
+    validator_index: usize,
+) -> Result<(), BlockProcessingError> {
+    if is_progressive_balances_enabled(state) {
+        let validator = state.get_validator(validator_index)?;
+        if !validator.slashed {
+            let validator_effective_balance = validator.effective_balance;
+            state
+                .progressive_balances_cache_mut()
+                .on_new_target_attestation(epoch, validator_effective_balance)?;
+        }
+    }
+    Ok(())
+}
+
+/// Updates the `ProgressiveBalancesCache` when a target attester has been slashed.
+pub fn update_progressive_balances_on_slashing<T: EthSpec>(
+    state: &mut BeaconState<T>,
+    validator_index: usize,
+) -> Result<(), BlockProcessingError> {
+    if is_progressive_balances_enabled(state) {
+        let previous_epoch_participation = state.previous_epoch_participation()?;
+        let is_previous_epoch_target_attester =
+            is_target_attester_in_epoch::<T>(previous_epoch_participation, validator_index)?;
+
+        let current_epoch_participation = state.current_epoch_participation()?;
+        let is_current_epoch_target_attester =
+            is_target_attester_in_epoch::<T>(current_epoch_participation, validator_index)?;
+
+        let validator_effective_balance = state.get_effective_balance(validator_index)?;
+
+        state.progressive_balances_cache_mut().on_slashing(
+            is_previous_epoch_target_attester,
+            is_current_epoch_target_attester,
+            validator_effective_balance,
+        )?;
+    }
+
+    Ok(())
+}
+
+/// Updates the `ProgressiveBalancesCache` on epoch transition.
+pub fn update_progressive_balances_on_epoch_transition<T: EthSpec>(
+    state: &mut BeaconState<T>,
+    spec: &ChainSpec,
+) -> Result<(), EpochProcessingError> {
+    if is_progressive_balances_enabled(state) {
+        state
+            .progressive_balances_cache_mut()
+            .on_epoch_transition(spec)?;
+
+        update_progressive_balances_metrics(state.progressive_balances_cache())?;
+    }
+
+    Ok(())
+}
+
+pub fn update_progressive_balances_metrics(
+    cache: &ProgressiveBalancesCache,
+) -> Result<(), BeaconStateError> {
+    set_gauge(
+        &PARTICIPATION_PREV_EPOCH_TARGET_ATTESTING_GWEI_PROGRESSIVE_TOTAL,
+        cache.previous_epoch_target_attesting_balance()? as i64,
+    );
+
+    set_gauge(
+        &PARTICIPATION_CURR_EPOCH_TARGET_ATTESTING_GWEI_PROGRESSIVE_TOTAL,
+        cache.current_epoch_target_attesting_balance()? as i64,
+    );
+
+    Ok(())
+}
+
+fn is_target_attester_in_epoch<T: EthSpec>(
+    epoch_participation: &VariableList<ParticipationFlags, T::ValidatorRegistryLimit>,
+    validator_index: usize,
+) -> Result<bool, BlockProcessingError> {
+    let participation_flags = epoch_participation
+        .get(validator_index)
+        .ok_or(BeaconStateError::UnknownValidator(validator_index))?;
+    participation_flags
+        .has_flag(TIMELY_TARGET_FLAG_INDEX)
+        .map_err(|e| e.into())
+}
diff --git a/consensus/state_processing/src/genesis.rs b/consensus/state_processing/src/genesis.rs
index 244cdc588..284a7019f 100644
--- a/consensus/state_processing/src/genesis.rs
+++ b/consensus/state_processing/src/genesis.rs
@@ -111,7 +111,7 @@ pub fn initialize_beacon_state_from_eth1<T: EthSpec>(
     }
 
     // Now that we have our validators, initialize the caches (including the committees)
-    state.build_all_caches(spec)?;
+    state.build_caches(spec)?;
 
     // Set genesis validators root for domain separation and chain versioning
     *state.genesis_validators_root_mut() = state.update_validators_tree_hash_cache()?;
@@ -134,7 +134,7 @@ pub fn process_activations<T: EthSpec>(
     state: &mut BeaconState<T>,
     spec: &ChainSpec,
 ) -> Result<(), Error> {
-    let (validators, balances) = state.validators_and_balances_mut();
+    let (validators, balances, _) = state.validators_and_balances_and_progressive_balances_mut();
     for (index, validator) in validators.iter_mut().enumerate() {
         let balance = balances
             .get(index)
diff --git a/consensus/state_processing/src/metrics.rs b/consensus/state_processing/src/metrics.rs
index ddfaae564..360b00767 100644
--- a/consensus/state_processing/src/metrics.rs
+++ b/consensus/state_processing/src/metrics.rs
@@ -23,4 +23,15 @@ lazy_static! {
         "beacon_participation_prev_epoch_active_gwei_total",
         "Total effective balance (gwei) of validators active in the previous epoch"
     );
+    /*
+     * Participation Metrics (progressive balances)
+     */
+    pub static ref PARTICIPATION_PREV_EPOCH_TARGET_ATTESTING_GWEI_PROGRESSIVE_TOTAL: Result<IntGauge> = try_create_int_gauge(
+        "beacon_participation_prev_epoch_target_attesting_gwei_progressive_total",
+        "Progressive total effective balance (gwei) of validators who attested to the target in the previous epoch"
+    );
+    pub static ref PARTICIPATION_CURR_EPOCH_TARGET_ATTESTING_GWEI_PROGRESSIVE_TOTAL: Result<IntGauge> = try_create_int_gauge(
+        "beacon_participation_curr_epoch_target_attesting_gwei_progressive_total",
+        "Progressive total effective balance (gwei) of validators who attested to the target in the current epoch"
+    );
 }
diff --git a/consensus/state_processing/src/per_block_processing.rs b/consensus/state_processing/src/per_block_processing.rs
index aee43c906..b9a147a5a 100644
--- a/consensus/state_processing/src/per_block_processing.rs
+++ b/consensus/state_processing/src/per_block_processing.rs
@@ -42,6 +42,9 @@ mod verify_proposer_slashing;
 use crate::common::decrease_balance;
 use crate::StateProcessingStrategy;
 
+use crate::common::update_progressive_balances_cache::{
+    initialize_progressive_balances_cache, update_progressive_balances_metrics,
+};
 #[cfg(feature = "arbitrary-fuzz")]
 use arbitrary::Arbitrary;
 
@@ -115,6 +118,8 @@ pub fn per_block_processing<T: EthSpec, Payload: AbstractExecPayload<T>>(
         .fork_name(spec)
         .map_err(BlockProcessingError::InconsistentStateFork)?;
 
+    initialize_progressive_balances_cache(state, None, spec)?;
+
     let verify_signatures = match block_signature_strategy {
         BlockSignatureStrategy::VerifyBulk => {
             // Verify all signatures in the block at once.
@@ -183,6 +188,10 @@ pub fn per_block_processing<T: EthSpec, Payload: AbstractExecPayload<T>>(
         )?;
     }
 
+    if is_progressive_balances_enabled(state) {
+        update_progressive_balances_metrics(state.progressive_balances_cache())?;
+    }
+
     Ok(())
 }
 
diff --git a/consensus/state_processing/src/per_block_processing/errors.rs b/consensus/state_processing/src/per_block_processing/errors.rs
index ab6db7e47..016460080 100644
--- a/consensus/state_processing/src/per_block_processing/errors.rs
+++ b/consensus/state_processing/src/per_block_processing/errors.rs
@@ -1,6 +1,8 @@
 use super::signature_sets::Error as SignatureSetError;
+use crate::per_epoch_processing::altair::participation_cache;
 use crate::ContextError;
 use merkle_proof::MerkleTreeError;
+use participation_cache::Error as ParticipationCacheError;
 use safe_arith::ArithError;
 use ssz::DecodeError;
 use types::*;
@@ -99,6 +101,7 @@ pub enum BlockProcessingError {
         length: usize,
     },
     WithdrawalCredentialsInvalid,
+    ParticipationCacheError(ParticipationCacheError),
 }
 
 impl From<BeaconStateError> for BlockProcessingError {
@@ -156,6 +159,12 @@ impl From<BlockOperationError<HeaderInvalid>> for BlockProcessingError {
     }
 }
 
+impl From<ParticipationCacheError> for BlockProcessingError {
+    fn from(e: ParticipationCacheError) -> Self {
+        BlockProcessingError::ParticipationCacheError(e)
+    }
+}
+
 /// A conversion that consumes `self` and adds an `index` variable to resulting struct.
 ///
 /// Used here to allow converting an error into an upstream error that points to the object that
diff --git a/consensus/state_processing/src/per_block_processing/process_operations.rs b/consensus/state_processing/src/per_block_processing/process_operations.rs
index 091f961db..4e60c4161 100644
--- a/consensus/state_processing/src/per_block_processing/process_operations.rs
+++ b/consensus/state_processing/src/per_block_processing/process_operations.rs
@@ -97,6 +97,8 @@ pub mod base {
 
 pub mod altair {
     use super::*;
+    use crate::common::update_progressive_balances_cache::update_progressive_balances_on_attestation;
+    use types::consts::altair::TIMELY_TARGET_FLAG_INDEX;
 
     pub fn process_attestations<T: EthSpec>(
         state: &mut BeaconState<T>,
@@ -163,6 +165,14 @@ pub mod altair {
                         get_base_reward(state, index, base_reward_per_increment, spec)?
                             .safe_mul(weight)?,
                     )?;
+
+                    if flag_index == TIMELY_TARGET_FLAG_INDEX {
+                        update_progressive_balances_on_attestation(
+                            state,
+                            data.target.epoch,
+                            index,
+                        )?;
+                    }
                 }
             }
         }
@@ -235,6 +245,7 @@ pub fn process_attester_slashings<T: EthSpec>(
 
     Ok(())
 }
+
 /// Wrapper function to handle calling the correct version of `process_attestations` based on
 /// the fork.
 pub fn process_attestations<T: EthSpec, Payload: AbstractExecPayload<T>>(
diff --git a/consensus/state_processing/src/per_epoch_processing/altair.rs b/consensus/state_processing/src/per_epoch_processing/altair.rs
index d5df2fc97..0abbd16a9 100644
--- a/consensus/state_processing/src/per_epoch_processing/altair.rs
+++ b/consensus/state_processing/src/per_epoch_processing/altair.rs
@@ -1,4 +1,7 @@
 use super::{process_registry_updates, process_slashings, EpochProcessingSummary, Error};
+use crate::common::update_progressive_balances_cache::{
+    initialize_progressive_balances_cache, update_progressive_balances_on_epoch_transition,
+};
 use crate::per_epoch_processing::{
     effective_balance_updates::process_effective_balance_updates,
     historical_roots_update::process_historical_roots_update,
@@ -31,6 +34,7 @@ pub fn process_epoch<T: EthSpec>(
     // Pre-compute participating indices and total balances.
     let participation_cache = ParticipationCache::new(state, spec)?;
     let sync_committee = state.current_sync_committee()?.clone();
+    initialize_progressive_balances_cache::<T>(state, Some(&participation_cache), spec)?;
 
     // Justification and finalization.
     let justification_and_finalization_state =
@@ -56,7 +60,7 @@ pub fn process_epoch<T: EthSpec>(
     process_eth1_data_reset(state)?;
 
     // Update effective balances with hysteresis (lag).
-    process_effective_balance_updates(state, spec)?;
+    process_effective_balance_updates(state, Some(&participation_cache), spec)?;
 
     // Reset slashings
     process_slashings_reset(state)?;
@@ -75,6 +79,8 @@ pub fn process_epoch<T: EthSpec>(
     // Rotate the epoch caches to suit the epoch transition.
     state.advance_caches(spec)?;
 
+    update_progressive_balances_on_epoch_transition(state, spec)?;
+
     Ok(EpochProcessingSummary::Altair {
         participation_cache,
         sync_committee,
diff --git a/consensus/state_processing/src/per_epoch_processing/altair/participation_cache.rs b/consensus/state_processing/src/per_epoch_processing/altair/participation_cache.rs
index 004726923..a5caddd04 100644
--- a/consensus/state_processing/src/per_epoch_processing/altair/participation_cache.rs
+++ b/consensus/state_processing/src/per_epoch_processing/altair/participation_cache.rs
@@ -11,49 +11,23 @@
 //! Additionally, this cache is returned from the `altair::process_epoch` function and can be used
 //! to get useful summaries about the validator participation in an epoch.
 
-use safe_arith::{ArithError, SafeArith};
 use types::{
     consts::altair::{
         NUM_FLAG_INDICES, TIMELY_HEAD_FLAG_INDEX, TIMELY_SOURCE_FLAG_INDEX,
         TIMELY_TARGET_FLAG_INDEX,
     },
-    BeaconState, BeaconStateError, ChainSpec, Epoch, EthSpec, ParticipationFlags, RelativeEpoch,
+    Balance, BeaconState, BeaconStateError, ChainSpec, Epoch, EthSpec, ParticipationFlags,
+    RelativeEpoch,
 };
 
-#[derive(Debug, PartialEq)]
+#[derive(Debug, PartialEq, Clone)]
 pub enum Error {
     InvalidFlagIndex(usize),
     InvalidValidatorIndex(usize),
 }
 
-/// A balance which will never be below the specified `minimum`.
-///
-/// This is an effort to ensure the `EFFECTIVE_BALANCE_INCREMENT` minimum is always respected.
-#[derive(PartialEq, Debug, Clone, Copy)]
-struct Balance {
-    raw: u64,
-    minimum: u64,
-}
-
-impl Balance {
-    /// Initialize the balance to `0`, or the given `minimum`.
-    pub fn zero(minimum: u64) -> Self {
-        Self { raw: 0, minimum }
-    }
-
-    /// Returns the balance with respect to the initialization `minimum`.
-    pub fn get(&self) -> u64 {
-        std::cmp::max(self.raw, self.minimum)
-    }
-
-    /// Add-assign to the balance.
-    pub fn safe_add_assign(&mut self, other: u64) -> Result<(), ArithError> {
-        self.raw.safe_add_assign(other)
-    }
-}
-
 /// Caches the participation values for one epoch (either the previous or current).
-#[derive(PartialEq, Debug)]
+#[derive(PartialEq, Debug, Clone)]
 struct SingleEpochParticipationCache {
     /// Maps an active validator index to their participation flags.
     ///
@@ -95,6 +69,14 @@ impl SingleEpochParticipationCache {
             .ok_or(Error::InvalidFlagIndex(flag_index))
     }
 
+    /// Returns the raw total balance of attesters who have `flag_index` set.
+    fn total_flag_balance_raw(&self, flag_index: usize) -> Result<Balance, Error> {
+        self.total_flag_balances
+            .get(flag_index)
+            .copied()
+            .ok_or(Error::InvalidFlagIndex(flag_index))
+    }
+
     /// Returns `true` if `val_index` is active, unslashed and has `flag_index` set.
     ///
     /// ## Errors
@@ -173,7 +155,7 @@ impl SingleEpochParticipationCache {
 }
 
 /// Maintains a cache to be used during `altair::process_epoch`.
-#[derive(PartialEq, Debug)]
+#[derive(PartialEq, Debug, Clone)]
 pub struct ParticipationCache {
     current_epoch: Epoch,
     /// Caches information about active validators pertaining to `self.current_epoch`.
@@ -291,6 +273,11 @@ impl ParticipationCache {
             .total_flag_balance(TIMELY_TARGET_FLAG_INDEX)
     }
 
+    pub fn current_epoch_target_attesting_balance_raw(&self) -> Result<Balance, Error> {
+        self.current_epoch_participation
+            .total_flag_balance_raw(TIMELY_TARGET_FLAG_INDEX)
+    }
+
     pub fn previous_epoch_total_active_balance(&self) -> u64 {
         self.previous_epoch_participation.total_active_balance.get()
     }
@@ -300,6 +287,11 @@ impl ParticipationCache {
             .total_flag_balance(TIMELY_TARGET_FLAG_INDEX)
     }
 
+    pub fn previous_epoch_target_attesting_balance_raw(&self) -> Result<Balance, Error> {
+        self.previous_epoch_participation
+            .total_flag_balance_raw(TIMELY_TARGET_FLAG_INDEX)
+    }
+
     pub fn previous_epoch_source_attesting_balance(&self) -> Result<u64, Error> {
         self.previous_epoch_participation
             .total_flag_balance(TIMELY_SOURCE_FLAG_INDEX)
diff --git a/consensus/state_processing/src/per_epoch_processing/base.rs b/consensus/state_processing/src/per_epoch_processing/base.rs
index cb7e7d4b3..680563ce7 100644
--- a/consensus/state_processing/src/per_epoch_processing/base.rs
+++ b/consensus/state_processing/src/per_epoch_processing/base.rs
@@ -52,7 +52,7 @@ pub fn process_epoch<T: EthSpec>(
     process_eth1_data_reset(state)?;
 
     // Update effective balances with hysteresis (lag).
-    process_effective_balance_updates(state, spec)?;
+    process_effective_balance_updates(state, None, spec)?;
 
     // Reset slashings
     process_slashings_reset(state)?;
diff --git a/consensus/state_processing/src/per_epoch_processing/capella.rs b/consensus/state_processing/src/per_epoch_processing/capella.rs
index aaf301f29..911510ed0 100644
--- a/consensus/state_processing/src/per_epoch_processing/capella.rs
+++ b/consensus/state_processing/src/per_epoch_processing/capella.rs
@@ -11,6 +11,9 @@ use crate::per_epoch_processing::{
 };
 use types::{BeaconState, ChainSpec, EthSpec, RelativeEpoch};
 
+use crate::common::update_progressive_balances_cache::{
+    initialize_progressive_balances_cache, update_progressive_balances_on_epoch_transition,
+};
 pub use historical_summaries_update::process_historical_summaries_update;
 
 mod historical_summaries_update;
@@ -27,6 +30,7 @@ pub fn process_epoch<T: EthSpec>(
     // Pre-compute participating indices and total balances.
     let participation_cache = ParticipationCache::new(state, spec)?;
     let sync_committee = state.current_sync_committee()?.clone();
+    initialize_progressive_balances_cache(state, Some(&participation_cache), spec)?;
 
     // Justification and finalization.
     let justification_and_finalization_state =
@@ -52,7 +56,7 @@ pub fn process_epoch<T: EthSpec>(
     process_eth1_data_reset(state)?;
 
     // Update effective balances with hysteresis (lag).
-    process_effective_balance_updates(state, spec)?;
+    process_effective_balance_updates(state, Some(&participation_cache), spec)?;
 
     // Reset slashings
     process_slashings_reset(state)?;
@@ -71,6 +75,8 @@ pub fn process_epoch<T: EthSpec>(
     // Rotate the epoch caches to suit the epoch transition.
     state.advance_caches(spec)?;
 
+    update_progressive_balances_on_epoch_transition(state, spec)?;
+
     Ok(EpochProcessingSummary::Altair {
         participation_cache,
         sync_committee,
diff --git a/consensus/state_processing/src/per_epoch_processing/effective_balance_updates.rs b/consensus/state_processing/src/per_epoch_processing/effective_balance_updates.rs
index c166667b5..1759f7e14 100644
--- a/consensus/state_processing/src/per_epoch_processing/effective_balance_updates.rs
+++ b/consensus/state_processing/src/per_epoch_processing/effective_balance_updates.rs
@@ -1,11 +1,13 @@
 use super::errors::EpochProcessingError;
+use crate::per_epoch_processing::altair::ParticipationCache;
 use safe_arith::SafeArith;
 use types::beacon_state::BeaconState;
 use types::chain_spec::ChainSpec;
-use types::{BeaconStateError, EthSpec};
+use types::{BeaconStateError, EthSpec, ProgressiveBalancesCache};
 
 pub fn process_effective_balance_updates<T: EthSpec>(
     state: &mut BeaconState<T>,
+    maybe_participation_cache: Option<&ParticipationCache>,
     spec: &ChainSpec,
 ) -> Result<(), EpochProcessingError> {
     let hysteresis_increment = spec
@@ -13,7 +15,8 @@ pub fn process_effective_balance_updates<T: EthSpec>(
         .safe_div(spec.hysteresis_quotient)?;
     let downward_threshold = hysteresis_increment.safe_mul(spec.hysteresis_downward_multiplier)?;
     let upward_threshold = hysteresis_increment.safe_mul(spec.hysteresis_upward_multiplier)?;
-    let (validators, balances) = state.validators_and_balances_mut();
+    let (validators, balances, progressive_balances_cache) =
+        state.validators_and_balances_and_progressive_balances_mut();
     for (index, validator) in validators.iter_mut().enumerate() {
         let balance = balances
             .get(index)
@@ -23,11 +26,43 @@ pub fn process_effective_balance_updates<T: EthSpec>(
         if balance.safe_add(downward_threshold)? < validator.effective_balance
             || validator.effective_balance.safe_add(upward_threshold)? < balance
         {
-            validator.effective_balance = std::cmp::min(
+            let old_effective_balance = validator.effective_balance;
+            let new_effective_balance = std::cmp::min(
                 balance.safe_sub(balance.safe_rem(spec.effective_balance_increment)?)?,
                 spec.max_effective_balance,
             );
+
+            if let Some(participation_cache) = maybe_participation_cache {
+                update_progressive_balances(
+                    participation_cache,
+                    progressive_balances_cache,
+                    index,
+                    old_effective_balance,
+                    new_effective_balance,
+                )?;
+            }
+
+            validator.effective_balance = new_effective_balance;
         }
     }
     Ok(())
 }
+
+fn update_progressive_balances(
+    participation_cache: &ParticipationCache,
+    progressive_balances_cache: &mut ProgressiveBalancesCache,
+    index: usize,
+    old_effective_balance: u64,
+    new_effective_balance: u64,
+) -> Result<(), EpochProcessingError> {
+    if old_effective_balance != new_effective_balance {
+        let is_current_epoch_target_attester =
+            participation_cache.is_current_epoch_timely_target_attester(index)?;
+        progressive_balances_cache.on_effective_balance_change(
+            is_current_epoch_target_attester,
+            old_effective_balance,
+            new_effective_balance,
+        )?;
+    }
+    Ok(())
+}
diff --git a/consensus/state_processing/src/per_epoch_processing/slashings.rs b/consensus/state_processing/src/per_epoch_processing/slashings.rs
index 6d5342cd3..2d595491c 100644
--- a/consensus/state_processing/src/per_epoch_processing/slashings.rs
+++ b/consensus/state_processing/src/per_epoch_processing/slashings.rs
@@ -16,7 +16,7 @@ pub fn process_slashings<T: EthSpec>(
         total_balance,
     );
 
-    let (validators, balances) = state.validators_and_balances_mut();
+    let (validators, balances, _) = state.validators_and_balances_and_progressive_balances_mut();
     for (index, validator) in validators.iter().enumerate() {
         if validator.slashed
             && epoch.safe_add(T::EpochsPerSlashingsVector::to_u64().safe_div(2)?)?
diff --git a/consensus/state_processing/src/upgrade/altair.rs b/consensus/state_processing/src/upgrade/altair.rs
index 176f1af15..26b1192bc 100644
--- a/consensus/state_processing/src/upgrade/altair.rs
+++ b/consensus/state_processing/src/upgrade/altair.rs
@@ -1,3 +1,4 @@
+use crate::common::update_progressive_balances_cache::initialize_progressive_balances_cache;
 use crate::common::{get_attestation_participation_flag_indices, get_attesting_indices};
 use std::mem;
 use std::sync::Arc;
@@ -101,6 +102,7 @@ pub fn upgrade_to_altair<E: EthSpec>(
         next_sync_committee: temp_sync_committee,            // not read
         // Caches
         total_active_balance: pre.total_active_balance,
+        progressive_balances_cache: mem::take(&mut pre.progressive_balances_cache),
         committee_caches: mem::take(&mut pre.committee_caches),
         pubkey_cache: mem::take(&mut pre.pubkey_cache),
         exit_cache: mem::take(&mut pre.exit_cache),
@@ -110,6 +112,8 @@ pub fn upgrade_to_altair<E: EthSpec>(
     // Fill in previous epoch participation from the pre state's pending attestations.
     translate_participation(&mut post, &pre.previous_epoch_attestations, spec)?;
 
+    initialize_progressive_balances_cache(&mut post, None, spec)?;
+
     // Fill in sync committees
     // Note: A duplicate committee is assigned for the current and next committee at the fork
     // boundary
diff --git a/consensus/state_processing/src/upgrade/capella.rs b/consensus/state_processing/src/upgrade/capella.rs
index 3b933fac3..5153e35f4 100644
--- a/consensus/state_processing/src/upgrade/capella.rs
+++ b/consensus/state_processing/src/upgrade/capella.rs
@@ -62,6 +62,7 @@ pub fn upgrade_to_capella<E: EthSpec>(
         historical_summaries: VariableList::default(),
         // Caches
         total_active_balance: pre.total_active_balance,
+        progressive_balances_cache: mem::take(&mut pre.progressive_balances_cache),
         committee_caches: mem::take(&mut pre.committee_caches),
         pubkey_cache: mem::take(&mut pre.pubkey_cache),
         exit_cache: mem::take(&mut pre.exit_cache),
diff --git a/consensus/state_processing/src/upgrade/merge.rs b/consensus/state_processing/src/upgrade/merge.rs
index c17246624..eb7445010 100644
--- a/consensus/state_processing/src/upgrade/merge.rs
+++ b/consensus/state_processing/src/upgrade/merge.rs
@@ -60,6 +60,7 @@ pub fn upgrade_to_bellatrix<E: EthSpec>(
         latest_execution_payload_header: <ExecutionPayloadHeaderMerge<E>>::default(),
         // Caches
         total_active_balance: pre.total_active_balance,
+        progressive_balances_cache: mem::take(&mut pre.progressive_balances_cache),
         committee_caches: mem::take(&mut pre.committee_caches),
         pubkey_cache: mem::take(&mut pre.pubkey_cache),
         exit_cache: mem::take(&mut pre.exit_cache),
diff --git a/consensus/types/Cargo.toml b/consensus/types/Cargo.toml
index 8db70dc85..883d5fe05 100644
--- a/consensus/types/Cargo.toml
+++ b/consensus/types/Cargo.toml
@@ -53,6 +53,7 @@ serde_json = "1.0.74"
 smallvec = "1.8.0"
 serde_with = "1.13.0"
 maplit = "1.0.2"
+strum = { version = "0.24.0", features = ["derive"] }
 
 [dev-dependencies]
 criterion = "0.3.3"
diff --git a/consensus/types/benches/benches.rs b/consensus/types/benches/benches.rs
index 28f57e708..bb2b52710 100644
--- a/consensus/types/benches/benches.rs
+++ b/consensus/types/benches/benches.rs
@@ -51,7 +51,7 @@ fn all_benches(c: &mut Criterion) {
     let spec = Arc::new(MainnetEthSpec::default_spec());
 
     let mut state = get_state::<MainnetEthSpec>(validator_count);
-    state.build_all_caches(&spec).expect("should build caches");
+    state.build_caches(&spec).expect("should build caches");
     let state_bytes = state.as_ssz_bytes();
 
     let inner_state = state.clone();
diff --git a/consensus/types/src/beacon_block_body.rs b/consensus/types/src/beacon_block_body.rs
index b88821715..61400a8b4 100644
--- a/consensus/types/src/beacon_block_body.rs
+++ b/consensus/types/src/beacon_block_body.rs
@@ -98,7 +98,7 @@ impl<'a, T: EthSpec, Payload: AbstractExecPayload<T>> BeaconBlockBodyRef<'a, T,
     }
 }
 
-impl<'a, T: EthSpec> BeaconBlockBodyRef<'a, T> {
+impl<'a, T: EthSpec, Payload: AbstractExecPayload<T>> BeaconBlockBodyRef<'a, T, Payload> {
     /// Get the fork_name of this object
     pub fn fork_name(self) -> ForkName {
         match self {
diff --git a/consensus/types/src/beacon_state.rs b/consensus/types/src/beacon_state.rs
index ca333048a..b09f2aa50 100644
--- a/consensus/types/src/beacon_state.rs
+++ b/consensus/types/src/beacon_state.rs
@@ -26,6 +26,8 @@ pub use self::committee_cache::{
     compute_committee_index_in_epoch, compute_committee_range_in_epoch, epoch_committee_count,
     CommitteeCache,
 };
+pub use crate::beacon_state::balance::Balance;
+pub use crate::beacon_state::progressive_balances_cache::*;
 use crate::historical_summary::HistoricalSummary;
 pub use clone_config::CloneConfig;
 pub use eth_spec::*;
@@ -34,9 +36,11 @@ pub use tree_hash_cache::BeaconTreeHashCache;
 
 #[macro_use]
 mod committee_cache;
+mod balance;
 mod clone_config;
 mod exit_cache;
 mod iter;
+mod progressive_balances_cache;
 mod pubkey_cache;
 mod tests;
 mod tree_hash_cache;
@@ -101,6 +105,9 @@ pub enum Error {
     SszTypesError(ssz_types::Error),
     TreeHashCacheNotInitialized,
     NonLinearTreeHashCacheHistory,
+    ParticipationCacheError(String),
+    ProgressiveBalancesCacheNotInitialized,
+    ProgressiveBalancesCacheInconsistent,
     TreeHashCacheSkippedSlot {
         cache: Slot,
         state: Slot,
@@ -322,6 +329,12 @@ where
     #[tree_hash(skip_hashing)]
     #[test_random(default)]
     #[derivative(Clone(clone_with = "clone_default"))]
+    pub progressive_balances_cache: ProgressiveBalancesCache,
+    #[serde(skip_serializing, skip_deserializing)]
+    #[ssz(skip_serializing, skip_deserializing)]
+    #[tree_hash(skip_hashing)]
+    #[test_random(default)]
+    #[derivative(Clone(clone_with = "clone_default"))]
     pub committee_caches: [CommitteeCache; CACHED_EPOCHS],
     #[serde(skip_serializing, skip_deserializing)]
     #[ssz(skip_serializing, skip_deserializing)]
@@ -398,6 +411,7 @@ impl<T: EthSpec> BeaconState<T> {
 
             // Caching (not in spec)
             total_active_balance: None,
+            progressive_balances_cache: <_>::default(),
             committee_caches: [
                 CommitteeCache::default(),
                 CommitteeCache::default(),
@@ -776,7 +790,7 @@ impl<T: EthSpec> BeaconState<T> {
         Ok(signature_hash_int.safe_rem(modulo)? == 0)
     }
 
-    /// Returns the beacon proposer index for the `slot` in the given `relative_epoch`.
+    /// Returns the beacon proposer index for the `slot` in `self.current_epoch()`.
     ///
     /// Spec v0.12.1
     pub fn get_beacon_proposer_index(&self, slot: Slot, spec: &ChainSpec) -> Result<usize, Error> {
@@ -1169,13 +1183,35 @@ impl<T: EthSpec> BeaconState<T> {
     }
 
     /// Convenience accessor for validators and balances simultaneously.
-    pub fn validators_and_balances_mut(&mut self) -> (&mut [Validator], &mut [u64]) {
+    pub fn validators_and_balances_and_progressive_balances_mut(
+        &mut self,
+    ) -> (&mut [Validator], &mut [u64], &mut ProgressiveBalancesCache) {
         match self {
-            BeaconState::Base(state) => (&mut state.validators, &mut state.balances),
-            BeaconState::Altair(state) => (&mut state.validators, &mut state.balances),
-            BeaconState::Merge(state) => (&mut state.validators, &mut state.balances),
-            BeaconState::Capella(state) => (&mut state.validators, &mut state.balances),
-            BeaconState::Deneb(state) => (&mut state.validators, &mut state.balances),
+            BeaconState::Base(state) => (
+                &mut state.validators,
+                &mut state.balances,
+                &mut state.progressive_balances_cache,
+            ),
+            BeaconState::Altair(state) => (
+                &mut state.validators,
+                &mut state.balances,
+                &mut state.progressive_balances_cache,
+            ),
+            BeaconState::Merge(state) => (
+                &mut state.validators,
+                &mut state.balances,
+                &mut state.progressive_balances_cache,
+            ),
+            BeaconState::Capella(state) => (
+                &mut state.validators,
+                &mut state.balances,
+                &mut state.progressive_balances_cache,
+            ),
+                        BeaconState::Deneb(state) => (
+                &mut state.validators,
+                &mut state.balances,
+                &mut state.progressive_balances_cache,
+            ),
         }
     }
 
@@ -1402,7 +1438,7 @@ impl<T: EthSpec> BeaconState<T> {
     }
 
     /// Build all caches (except the tree hash cache), if they need to be built.
-    pub fn build_all_caches(&mut self, spec: &ChainSpec) -> Result<(), Error> {
+    pub fn build_caches(&mut self, spec: &ChainSpec) -> Result<(), Error> {
         self.build_all_committee_caches(spec)?;
         self.update_pubkey_cache()?;
         self.build_exit_cache(spec)?;
@@ -1434,6 +1470,7 @@ impl<T: EthSpec> BeaconState<T> {
         self.drop_committee_cache(RelativeEpoch::Next)?;
         self.drop_pubkey_cache();
         self.drop_tree_hash_cache();
+        self.drop_progressive_balances_cache();
         *self.exit_cache_mut() = ExitCache::default();
         Ok(())
     }
@@ -1630,6 +1667,11 @@ impl<T: EthSpec> BeaconState<T> {
         *self.pubkey_cache_mut() = PubkeyCache::default()
     }
 
+    /// Completely drops the `progressive_balances_cache` cache, replacing it with a new, empty cache.
+    fn drop_progressive_balances_cache(&mut self) {
+        *self.progressive_balances_cache_mut() = ProgressiveBalancesCache::default();
+    }
+
     /// Initialize but don't fill the tree hash cache, if it isn't already initialized.
     pub fn initialize_tree_hash_cache(&mut self) {
         if !self.tree_hash_cache().is_initialized() {
@@ -1702,6 +1744,9 @@ impl<T: EthSpec> BeaconState<T> {
         if config.tree_hash_cache {
             *res.tree_hash_cache_mut() = self.tree_hash_cache().clone();
         }
+        if config.progressive_balances_cache {
+            *res.progressive_balances_cache_mut() = self.progressive_balances_cache().clone();
+        }
         res
     }
 
diff --git a/consensus/types/src/beacon_state/balance.rs b/consensus/types/src/beacon_state/balance.rs
new file mode 100644
index 000000000..e537a5b98
--- /dev/null
+++ b/consensus/types/src/beacon_state/balance.rs
@@ -0,0 +1,33 @@
+use arbitrary::Arbitrary;
+use safe_arith::{ArithError, SafeArith};
+
+/// A balance which will never be below the specified `minimum`.
+///
+/// This is an effort to ensure the `EFFECTIVE_BALANCE_INCREMENT` minimum is always respected.
+#[derive(PartialEq, Debug, Clone, Copy, Arbitrary)]
+pub struct Balance {
+    raw: u64,
+    minimum: u64,
+}
+
+impl Balance {
+    /// Initialize the balance to `0`, or the given `minimum`.
+    pub fn zero(minimum: u64) -> Self {
+        Self { raw: 0, minimum }
+    }
+
+    /// Returns the balance with respect to the initialization `minimum`.
+    pub fn get(&self) -> u64 {
+        std::cmp::max(self.raw, self.minimum)
+    }
+
+    /// Add-assign to the balance.
+    pub fn safe_add_assign(&mut self, other: u64) -> Result<(), ArithError> {
+        self.raw.safe_add_assign(other)
+    }
+
+    /// Sub-assign to the balance.
+    pub fn safe_sub_assign(&mut self, other: u64) -> Result<(), ArithError> {
+        self.raw.safe_sub_assign(other)
+    }
+}
diff --git a/consensus/types/src/beacon_state/clone_config.rs b/consensus/types/src/beacon_state/clone_config.rs
index e5f050aee..c6e7f4742 100644
--- a/consensus/types/src/beacon_state/clone_config.rs
+++ b/consensus/types/src/beacon_state/clone_config.rs
@@ -5,6 +5,7 @@ pub struct CloneConfig {
     pub pubkey_cache: bool,
     pub exit_cache: bool,
     pub tree_hash_cache: bool,
+    pub progressive_balances_cache: bool,
 }
 
 impl CloneConfig {
@@ -14,6 +15,7 @@ impl CloneConfig {
             pubkey_cache: true,
             exit_cache: true,
             tree_hash_cache: true,
+            progressive_balances_cache: true,
         }
     }
 
diff --git a/consensus/types/src/beacon_state/progressive_balances_cache.rs b/consensus/types/src/beacon_state/progressive_balances_cache.rs
new file mode 100644
index 000000000..9f5c223d5
--- /dev/null
+++ b/consensus/types/src/beacon_state/progressive_balances_cache.rs
@@ -0,0 +1,184 @@
+use crate::beacon_state::balance::Balance;
+use crate::{BeaconState, BeaconStateError, ChainSpec, Epoch, EthSpec};
+use arbitrary::Arbitrary;
+use safe_arith::SafeArith;
+use serde_derive::{Deserialize, Serialize};
+use strum::{Display, EnumString, EnumVariantNames};
+
+/// This cache keeps track of the accumulated target attestation balance for the current & previous
+/// epochs. The cached values can be utilised by fork choice to calculate unrealized justification
+/// and finalization instead of converting epoch participation arrays to balances for each block we
+/// process.
+#[derive(Default, Debug, PartialEq, Arbitrary, Clone)]
+pub struct ProgressiveBalancesCache {
+    inner: Option<Inner>,
+}
+
+#[derive(Debug, PartialEq, Arbitrary, Clone)]
+struct Inner {
+    pub current_epoch: Epoch,
+    pub previous_epoch_target_attesting_balance: Balance,
+    pub current_epoch_target_attesting_balance: Balance,
+}
+
+impl ProgressiveBalancesCache {
+    pub fn initialize(
+        &mut self,
+        current_epoch: Epoch,
+        previous_epoch_target_attesting_balance: Balance,
+        current_epoch_target_attesting_balance: Balance,
+    ) {
+        self.inner = Some(Inner {
+            current_epoch,
+            previous_epoch_target_attesting_balance,
+            current_epoch_target_attesting_balance,
+        });
+    }
+
+    pub fn is_initialized(&self) -> bool {
+        self.inner.is_some()
+    }
+
+    /// When a new target attestation has been processed, we update the cached
+    /// `current_epoch_target_attesting_balance` to include the validator effective balance.
+    /// If the epoch is neither the current epoch nor the previous epoch, an error is returned.
+    pub fn on_new_target_attestation(
+        &mut self,
+        epoch: Epoch,
+        validator_effective_balance: u64,
+    ) -> Result<(), BeaconStateError> {
+        let cache = self.get_inner_mut()?;
+
+        if epoch == cache.current_epoch {
+            cache
+                .current_epoch_target_attesting_balance
+                .safe_add_assign(validator_effective_balance)?;
+        } else if epoch.safe_add(1)? == cache.current_epoch {
+            cache
+                .previous_epoch_target_attesting_balance
+                .safe_add_assign(validator_effective_balance)?;
+        } else {
+            return Err(BeaconStateError::ProgressiveBalancesCacheInconsistent);
+        }
+
+        Ok(())
+    }
+
+    /// When a validator is slashed, we reduce the `current_epoch_target_attesting_balance` by the
+    /// validator's effective balance to exclude the validator weight.
+    pub fn on_slashing(
+        &mut self,
+        is_previous_epoch_target_attester: bool,
+        is_current_epoch_target_attester: bool,
+        effective_balance: u64,
+    ) -> Result<(), BeaconStateError> {
+        let cache = self.get_inner_mut()?;
+        if is_previous_epoch_target_attester {
+            cache
+                .previous_epoch_target_attesting_balance
+                .safe_sub_assign(effective_balance)?;
+        }
+        if is_current_epoch_target_attester {
+            cache
+                .current_epoch_target_attesting_balance
+                .safe_sub_assign(effective_balance)?;
+        }
+        Ok(())
+    }
+
+    /// When a current epoch target attester has its effective balance changed, we adjust the
+    /// its share of the target attesting balance in the cache.
+    pub fn on_effective_balance_change(
+        &mut self,
+        is_current_epoch_target_attester: bool,
+        old_effective_balance: u64,
+        new_effective_balance: u64,
+    ) -> Result<(), BeaconStateError> {
+        let cache = self.get_inner_mut()?;
+        if is_current_epoch_target_attester {
+            if new_effective_balance > old_effective_balance {
+                cache
+                    .current_epoch_target_attesting_balance
+                    .safe_add_assign(new_effective_balance.safe_sub(old_effective_balance)?)?;
+            } else {
+                cache
+                    .current_epoch_target_attesting_balance
+                    .safe_sub_assign(old_effective_balance.safe_sub(new_effective_balance)?)?;
+            }
+        }
+        Ok(())
+    }
+
+    /// On epoch transition, the balance from current epoch is shifted to previous epoch, and the
+    /// current epoch balance is reset to 0.
+    pub fn on_epoch_transition(&mut self, spec: &ChainSpec) -> Result<(), BeaconStateError> {
+        let cache = self.get_inner_mut()?;
+        cache.current_epoch.safe_add_assign(1)?;
+        cache.previous_epoch_target_attesting_balance =
+            cache.current_epoch_target_attesting_balance;
+        cache.current_epoch_target_attesting_balance =
+            Balance::zero(spec.effective_balance_increment);
+        Ok(())
+    }
+
+    pub fn previous_epoch_target_attesting_balance(&self) -> Result<u64, BeaconStateError> {
+        Ok(self
+            .get_inner()?
+            .previous_epoch_target_attesting_balance
+            .get())
+    }
+
+    pub fn current_epoch_target_attesting_balance(&self) -> Result<u64, BeaconStateError> {
+        Ok(self
+            .get_inner()?
+            .current_epoch_target_attesting_balance
+            .get())
+    }
+
+    fn get_inner_mut(&mut self) -> Result<&mut Inner, BeaconStateError> {
+        self.inner
+            .as_mut()
+            .ok_or(BeaconStateError::ProgressiveBalancesCacheNotInitialized)
+    }
+
+    fn get_inner(&self) -> Result<&Inner, BeaconStateError> {
+        self.inner
+            .as_ref()
+            .ok_or(BeaconStateError::ProgressiveBalancesCacheNotInitialized)
+    }
+}
+
+#[derive(
+    Debug, PartialEq, Eq, Clone, Copy, Deserialize, Serialize, Display, EnumString, EnumVariantNames,
+)]
+#[strum(serialize_all = "lowercase")]
+pub enum ProgressiveBalancesMode {
+    /// Disable the usage of progressive cache, and use the existing `ParticipationCache` calculation.
+    Disabled,
+    /// Enable the usage of progressive cache, with checks against the `ParticipationCache` and falls
+    /// back to the existing calculation if there is a balance mismatch.
+    Checked,
+    /// Enable the usage of progressive cache, with checks against the `ParticipationCache`. Errors
+    /// if there is a balance mismatch. Used in testing only.
+    Strict,
+    /// Enable the usage of progressive cache, with no comparative checks against the
+    /// `ParticipationCache`. This is fast but an experimental mode, use with caution.
+    Fast,
+}
+
+impl ProgressiveBalancesMode {
+    pub fn perform_comparative_checks(&self) -> bool {
+        match self {
+            Self::Disabled | Self::Fast => false,
+            Self::Checked | Self::Strict => true,
+        }
+    }
+}
+
+/// `ProgressiveBalancesCache` is only enabled from `Altair` as it requires `ParticipationCache`.
+pub fn is_progressive_balances_enabled<E: EthSpec>(state: &BeaconState<E>) -> bool {
+    match state {
+        BeaconState::Base(_) => false,
+        BeaconState::Altair(_) | BeaconState::Merge(_) | BeaconState::Capella(_) => true,
+    }
+}
diff --git a/consensus/types/src/beacon_state/tests.rs b/consensus/types/src/beacon_state/tests.rs
index d63eaafc4..6cd9c1dbf 100644
--- a/consensus/types/src/beacon_state/tests.rs
+++ b/consensus/types/src/beacon_state/tests.rs
@@ -219,17 +219,18 @@ async fn clone_config() {
 
     let mut state = build_state::<MinimalEthSpec>(16).await;
 
-    state.build_all_caches(&spec).unwrap();
+    state.build_caches(&spec).unwrap();
     state
         .update_tree_hash_cache()
         .expect("should update tree hash cache");
 
-    let num_caches = 4;
+    let num_caches = 5;
     let all_configs = (0..2u8.pow(num_caches)).map(|i| CloneConfig {
         committee_caches: (i & 1) != 0,
         pubkey_cache: ((i >> 1) & 1) != 0,
         exit_cache: ((i >> 2) & 1) != 0,
         tree_hash_cache: ((i >> 3) & 1) != 0,
+        progressive_balances_cache: ((i >> 4) & 1) != 0,
     });
 
     for config in all_configs {
diff --git a/lcli/Cargo.toml b/lcli/Cargo.toml
index 185da02d0..3e0754240 100644
--- a/lcli/Cargo.toml
+++ b/lcli/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "lcli"
 description = "Lighthouse CLI (modeled after zcli)"
-version = "4.2.0"
+version = "4.3.0"
 authors = ["Paul Hauner <paul@paulhauner.com>"]
 edition = "2021"
 
diff --git a/lcli/src/new_testnet.rs b/lcli/src/new_testnet.rs
index eaf963a8c..3c5e0fe2b 100644
--- a/lcli/src/new_testnet.rs
+++ b/lcli/src/new_testnet.rs
@@ -329,7 +329,7 @@ fn initialize_state_with_validators<T: EthSpec>(
     }
 
     // Now that we have our validators, initialize the caches (including the committees)
-    state.build_all_caches(spec).unwrap();
+    state.build_caches(spec).unwrap();
 
     // Set genesis validators root for domain separation and chain versioning
     *state.genesis_validators_root_mut() = state.update_validators_tree_hash_cache().unwrap();
diff --git a/lcli/src/skip_slots.rs b/lcli/src/skip_slots.rs
index 49d1dd424..e3b2a5acb 100644
--- a/lcli/src/skip_slots.rs
+++ b/lcli/src/skip_slots.rs
@@ -109,7 +109,7 @@ pub fn run<T: EthSpec>(env: Environment<T>, matches: &ArgMatches) -> Result<(),
     let target_slot = initial_slot + slots;
 
     state
-        .build_all_caches(spec)
+        .build_caches(spec)
         .map_err(|e| format!("Unable to build caches: {:?}", e))?;
 
     let state_root = if let Some(root) = cli_state_root.or(state_root) {
diff --git a/lcli/src/transition_blocks.rs b/lcli/src/transition_blocks.rs
index cf971c69f..34a456076 100644
--- a/lcli/src/transition_blocks.rs
+++ b/lcli/src/transition_blocks.rs
@@ -205,7 +205,7 @@ pub fn run<T: EthSpec>(env: Environment<T>, matches: &ArgMatches) -> Result<(),
 
     if config.exclude_cache_builds {
         pre_state
-            .build_all_caches(spec)
+            .build_caches(spec)
             .map_err(|e| format!("Unable to build caches: {:?}", e))?;
         let state_root = pre_state
             .update_tree_hash_cache()
@@ -303,7 +303,7 @@ fn do_transition<T: EthSpec>(
     if !config.exclude_cache_builds {
         let t = Instant::now();
         pre_state
-            .build_all_caches(spec)
+            .build_caches(spec)
             .map_err(|e| format!("Unable to build caches: {:?}", e))?;
         debug!("Build caches: {:?}", t.elapsed());
 
@@ -335,7 +335,7 @@ fn do_transition<T: EthSpec>(
 
     let t = Instant::now();
     pre_state
-        .build_all_caches(spec)
+        .build_caches(spec)
         .map_err(|e| format!("Unable to build caches: {:?}", e))?;
     debug!("Build all caches (again): {:?}", t.elapsed());
 
diff --git a/lighthouse/Cargo.toml b/lighthouse/Cargo.toml
index ae79972e9..050ea2841 100644
--- a/lighthouse/Cargo.toml
+++ b/lighthouse/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "lighthouse"
-version = "4.2.0"
+version = "4.3.0"
 authors = ["Sigma Prime <contact@sigmaprime.io>"]
 edition = "2021"
 autotests = false
diff --git a/lighthouse/tests/beacon_node.rs b/lighthouse/tests/beacon_node.rs
index 84bc2966c..bc5b69054 100644
--- a/lighthouse/tests/beacon_node.rs
+++ b/lighthouse/tests/beacon_node.rs
@@ -16,7 +16,10 @@ use std::str::FromStr;
 use std::string::ToString;
 use std::time::Duration;
 use tempfile::TempDir;
-use types::{Address, Checkpoint, Epoch, ExecutionBlockHash, ForkName, Hash256, MainnetEthSpec};
+use types::{
+    Address, Checkpoint, Epoch, ExecutionBlockHash, ForkName, Hash256, MainnetEthSpec,
+    ProgressiveBalancesMode,
+};
 use unused_port::{unused_tcp4_port, unused_tcp6_port, unused_udp4_port, unused_udp6_port};
 
 const DEFAULT_ETH1_ENDPOINT: &str = "http://localhost:8545/";
@@ -1125,48 +1128,13 @@ fn default_backfill_rate_limiting_flag() {
 }
 #[test]
 fn default_boot_nodes() {
-    let mainnet = vec![
-    // Lighthouse Team (Sigma Prime)
-    "enr:-Jq4QItoFUuug_n_qbYbU0OY04-np2wT8rUCauOOXNi0H3BWbDj-zbfZb7otA7jZ6flbBpx1LNZK2TDebZ9dEKx84LYBhGV0aDKQtTA_KgEAAAD__________4JpZIJ2NIJpcISsaa0ZiXNlY3AyNTZrMaEDHAD2JKYevx89W0CcFJFiskdcEzkH_Wdv9iW42qLK79ODdWRwgiMo",
-    "enr:-Jq4QN_YBsUOqQsty1OGvYv48PMaiEt1AzGD1NkYQHaxZoTyVGqMYXg0K9c0LPNWC9pkXmggApp8nygYLsQwScwAgfgBhGV0aDKQtTA_KgEAAAD__________4JpZIJ2NIJpcISLosQxiXNlY3AyNTZrMaEDBJj7_dLFACaxBfaI8KZTh_SSJUjhyAyfshimvSqo22WDdWRwgiMo",
-    // EF Team
-    "enr:-Ku4QHqVeJ8PPICcWk1vSn_XcSkjOkNiTg6Fmii5j6vUQgvzMc9L1goFnLKgXqBJspJjIsB91LTOleFmyWWrFVATGngBh2F0dG5ldHOIAAAAAAAAAACEZXRoMpC1MD8qAAAAAP__________gmlkgnY0gmlwhAMRHkWJc2VjcDI1NmsxoQKLVXFOhp2uX6jeT0DvvDpPcU8FWMjQdR4wMuORMhpX24N1ZHCCIyg",
-    "enr:-Ku4QG-2_Md3sZIAUebGYT6g0SMskIml77l6yR-M_JXc-UdNHCmHQeOiMLbylPejyJsdAPsTHJyjJB2sYGDLe0dn8uYBh2F0dG5ldHOIAAAAAAAAAACEZXRoMpC1MD8qAAAAAP__________gmlkgnY0gmlwhBLY-NyJc2VjcDI1NmsxoQORcM6e19T1T9gi7jxEZjk_sjVLGFscUNqAY9obgZaxbIN1ZHCCIyg",
-    "enr:-Ku4QPn5eVhcoF1opaFEvg1b6JNFD2rqVkHQ8HApOKK61OIcIXD127bKWgAtbwI7pnxx6cDyk_nI88TrZKQaGMZj0q0Bh2F0dG5ldHOIAAAAAAAAAACEZXRoMpC1MD8qAAAAAP__________gmlkgnY0gmlwhDayLMaJc2VjcDI1NmsxoQK2sBOLGcUb4AwuYzFuAVCaNHA-dy24UuEKkeFNgCVCsIN1ZHCCIyg",
-    "enr:-Ku4QEWzdnVtXc2Q0ZVigfCGggOVB2Vc1ZCPEc6j21NIFLODSJbvNaef1g4PxhPwl_3kax86YPheFUSLXPRs98vvYsoBh2F0dG5ldHOIAAAAAAAAAACEZXRoMpC1MD8qAAAAAP__________gmlkgnY0gmlwhDZBrP2Jc2VjcDI1NmsxoQM6jr8Rb1ktLEsVcKAPa08wCsKUmvoQ8khiOl_SLozf9IN1ZHCCIyg",
-    // Teku team (Consensys)
-    "enr:-KG4QOtcP9X1FbIMOe17QNMKqDxCpm14jcX5tiOE4_TyMrFqbmhPZHK_ZPG2Gxb1GE2xdtodOfx9-cgvNtxnRyHEmC0ghGV0aDKQ9aX9QgAAAAD__________4JpZIJ2NIJpcIQDE8KdiXNlY3AyNTZrMaEDhpehBDbZjM_L9ek699Y7vhUJ-eAdMyQW_Fil522Y0fODdGNwgiMog3VkcIIjKA",
-    "enr:-KG4QDyytgmE4f7AnvW-ZaUOIi9i79qX4JwjRAiXBZCU65wOfBu-3Nb5I7b_Rmg3KCOcZM_C3y5pg7EBU5XGrcLTduQEhGV0aDKQ9aX9QgAAAAD__________4JpZIJ2NIJpcIQ2_DUbiXNlY3AyNTZrMaEDKnz_-ps3UUOfHWVYaskI5kWYO_vtYMGYCQRAR3gHDouDdGNwgiMog3VkcIIjKA",
-    // Prysm team (Prysmatic Labs)
-    "enr:-Ku4QImhMc1z8yCiNJ1TyUxdcfNucje3BGwEHzodEZUan8PherEo4sF7pPHPSIB1NNuSg5fZy7qFsjmUKs2ea1Whi0EBh2F0dG5ldHOIAAAAAAAAAACEZXRoMpD1pf1CAAAAAP__________gmlkgnY0gmlwhBLf22SJc2VjcDI1NmsxoQOVphkDqal4QzPMksc5wnpuC3gvSC8AfbFOnZY_On34wIN1ZHCCIyg",
-    "enr:-Ku4QP2xDnEtUXIjzJ_DhlCRN9SN99RYQPJL92TMlSv7U5C1YnYLjwOQHgZIUXw6c-BvRg2Yc2QsZxxoS_pPRVe0yK8Bh2F0dG5ldHOIAAAAAAAAAACEZXRoMpD1pf1CAAAAAP__________gmlkgnY0gmlwhBLf22SJc2VjcDI1NmsxoQMeFF5GrS7UZpAH2Ly84aLK-TyvH-dRo0JM1i8yygH50YN1ZHCCJxA",
-    "enr:-Ku4QPp9z1W4tAO8Ber_NQierYaOStqhDqQdOPY3bB3jDgkjcbk6YrEnVYIiCBbTxuar3CzS528d2iE7TdJsrL-dEKoBh2F0dG5ldHOIAAAAAAAAAACEZXRoMpD1pf1CAAAAAP__________gmlkgnY0gmlwhBLf22SJc2VjcDI1NmsxoQMw5fqqkw2hHC4F5HZZDPsNmPdB1Gi8JPQK7pRc9XHh-oN1ZHCCKvg",
-    // Nimbus team
-    "enr:-LK4QA8FfhaAjlb_BXsXxSfiysR7R52Nhi9JBt4F8SPssu8hdE1BXQQEtVDC3qStCW60LSO7hEsVHv5zm8_6Vnjhcn0Bh2F0dG5ldHOIAAAAAAAAAACEZXRoMpC1MD8qAAAAAP__________gmlkgnY0gmlwhAN4aBKJc2VjcDI1NmsxoQJerDhsJ-KxZ8sHySMOCmTO6sHM3iCFQ6VMvLTe948MyYN0Y3CCI4yDdWRwgiOM",
-    "enr:-LK4QKWrXTpV9T78hNG6s8AM6IO4XH9kFT91uZtFg1GcsJ6dKovDOr1jtAAFPnS2lvNltkOGA9k29BUN7lFh_sjuc9QBh2F0dG5ldHOIAAAAAAAAAACEZXRoMpC1MD8qAAAAAP__________gmlkgnY0gmlwhANAdd-Jc2VjcDI1NmsxoQLQa6ai7y9PMN5hpLe5HmiJSlYzMuzP7ZhwRiwHvqNXdoN0Y3CCI4yDdWRwgiOM"
-    ];
+    let number_of_boot_nodes = 15;
 
     CommandLineTest::new()
         .run_with_zero_port()
         .with_config(|config| {
             // Lighthouse Team (Sigma Prime)
-            assert_eq!(config.network.boot_nodes_enr[0].to_base64(), mainnet[0]);
-            assert_eq!(config.network.boot_nodes_enr[1].to_base64(), mainnet[1]);
-            // EF Team
-            assert_eq!(config.network.boot_nodes_enr[2].to_base64(), mainnet[2]);
-            assert_eq!(config.network.boot_nodes_enr[3].to_base64(), mainnet[3]);
-            assert_eq!(config.network.boot_nodes_enr[4].to_base64(), mainnet[4]);
-            assert_eq!(config.network.boot_nodes_enr[5].to_base64(), mainnet[5]);
-            // Teku team (Consensys)
-            assert_eq!(config.network.boot_nodes_enr[6].to_base64(), mainnet[6]);
-            assert_eq!(config.network.boot_nodes_enr[7].to_base64(), mainnet[7]);
-            // Prysm team (Prysmatic Labs)
-            assert_eq!(config.network.boot_nodes_enr[8].to_base64(), mainnet[8]);
-            assert_eq!(config.network.boot_nodes_enr[9].to_base64(), mainnet[9]);
-            assert_eq!(config.network.boot_nodes_enr[10].to_base64(), mainnet[10]);
-            // Nimbus team
-            assert_eq!(config.network.boot_nodes_enr[11].to_base64(), mainnet[11]);
-            assert_eq!(config.network.boot_nodes_enr[12].to_base64(), mainnet[12]);
+            assert_eq!(config.network.boot_nodes_enr.len(), number_of_boot_nodes);
         });
 }
 #[test]
@@ -2323,3 +2291,28 @@ fn invalid_gossip_verified_blocks_path() {
             )
         });
 }
+
+#[test]
+fn progressive_balances_default() {
+    CommandLineTest::new()
+        .run_with_zero_port()
+        .with_config(|config| {
+            assert_eq!(
+                config.chain.progressive_balances_mode,
+                ProgressiveBalancesMode::Checked
+            )
+        });
+}
+
+#[test]
+fn progressive_balances_fast() {
+    CommandLineTest::new()
+        .flag("progressive-balances", Some("fast"))
+        .run_with_zero_port()
+        .with_config(|config| {
+            assert_eq!(
+                config.chain.progressive_balances_mode,
+                ProgressiveBalancesMode::Fast
+            )
+        });
+}
diff --git a/testing/ef_tests/src/cases/epoch_processing.rs b/testing/ef_tests/src/cases/epoch_processing.rs
index 34c4a74a9..5f2b8403f 100644
--- a/testing/ef_tests/src/cases/epoch_processing.rs
+++ b/testing/ef_tests/src/cases/epoch_processing.rs
@@ -6,9 +6,9 @@ use crate::type_name;
 use crate::type_name::TypeName;
 use serde_derive::Deserialize;
 use state_processing::per_epoch_processing::capella::process_historical_summaries_update;
+use state_processing::per_epoch_processing::effective_balance_updates::process_effective_balance_updates;
 use state_processing::per_epoch_processing::{
     altair, base,
-    effective_balance_updates::process_effective_balance_updates,
     historical_roots_update::process_historical_roots_update,
     process_registry_updates, process_slashings,
     resets::{process_eth1_data_reset, process_randao_mixes_reset, process_slashings_reset},
@@ -180,7 +180,7 @@ impl<E: EthSpec> EpochTransition<E> for Eth1DataReset {
 
 impl<E: EthSpec> EpochTransition<E> for EffectiveBalanceUpdates {
     fn run(state: &mut BeaconState<E>, spec: &ChainSpec) -> Result<(), EpochProcessingError> {
-        process_effective_balance_updates(state, spec)
+        process_effective_balance_updates(state, None, spec)
     }
 }
 
diff --git a/testing/ef_tests/src/cases/fork_choice.rs b/testing/ef_tests/src/cases/fork_choice.rs
index e4cf9f1ee..8c4a90044 100644
--- a/testing/ef_tests/src/cases/fork_choice.rs
+++ b/testing/ef_tests/src/cases/fork_choice.rs
@@ -18,7 +18,8 @@ use std::sync::Arc;
 use std::time::Duration;
 use types::{
     Attestation, AttesterSlashing, BeaconBlock, BeaconState, Checkpoint, EthSpec,
-    ExecutionBlockHash, ForkName, Hash256, IndexedAttestation, SignedBeaconBlock, Slot, Uint256,
+    ExecutionBlockHash, ForkName, Hash256, IndexedAttestation, ProgressiveBalancesMode,
+    SignedBeaconBlock, Slot, Uint256,
 };
 
 #[derive(Default, Debug, PartialEq, Clone, Deserialize, Decode)]
@@ -382,6 +383,7 @@ impl<E: EthSpec> Tester<E> {
             block_root,
             block.clone(),
             NotifyExecutionLayer::Yes,
+            || Ok(()),
         ))?;
         if result.is_ok() != valid {
             return Err(Error::DidntFail(format!(
@@ -439,7 +441,9 @@ impl<E: EthSpec> Tester<E> {
                         block_delay,
                         &state,
                         PayloadVerificationStatus::Irrelevant,
+                        ProgressiveBalancesMode::Strict,
                         &self.harness.chain.spec,
+                        self.harness.logger(),
                     );
 
                 if result.is_ok() {
diff --git a/testing/ef_tests/src/cases/operations.rs b/testing/ef_tests/src/cases/operations.rs
index 002558d6b..59aa51228 100644
--- a/testing/ef_tests/src/cases/operations.rs
+++ b/testing/ef_tests/src/cases/operations.rs
@@ -4,6 +4,7 @@ use crate::case_result::compare_beacon_state_results_without_caches;
 use crate::decode::{ssz_decode_file, ssz_decode_file_with, ssz_decode_state, yaml_decode_file};
 use crate::testing_spec;
 use serde_derive::Deserialize;
+use state_processing::common::update_progressive_balances_cache::initialize_progressive_balances_cache;
 use ssz::Decode;
 use state_processing::{
     per_block_processing::{
@@ -97,10 +98,8 @@ impl<E: EthSpec> Operation<E> for Attestation<E> {
                 &mut ctxt,
                 spec,
             ),
-            BeaconState::Altair(_)
-            | BeaconState::Merge(_)
-            | BeaconState::Capella(_)
-            | BeaconState::Deneb(_) => {
+            BeaconState::Altair(_) | BeaconState::Merge(_) | BeaconState::Capella(_)| BeaconState::Deneb(_) => {
+                initialize_progressive_balances_cache(state, None, spec)?;
                 altair::process_attestation(state, self, 0, &mut ctxt, VerifySignatures::True, spec)
             }
         }
@@ -123,6 +122,7 @@ impl<E: EthSpec> Operation<E> for AttesterSlashing<E> {
         _: &Operations<E, Self>,
     ) -> Result<(), BlockProcessingError> {
         let mut ctxt = ConsensusContext::new(state.slot());
+        initialize_progressive_balances_cache(state, None, spec)?;
         process_attester_slashings(
             state,
             &[self.clone()],
@@ -173,6 +173,7 @@ impl<E: EthSpec> Operation<E> for ProposerSlashing {
         _: &Operations<E, Self>,
     ) -> Result<(), BlockProcessingError> {
         let mut ctxt = ConsensusContext::new(state.slot());
+        initialize_progressive_balances_cache(state, None, spec)?;
         process_proposer_slashings(
             state,
             &[self.clone()],
diff --git a/testing/ef_tests/src/cases/sanity_blocks.rs b/testing/ef_tests/src/cases/sanity_blocks.rs
index e51fed190..191b45c33 100644
--- a/testing/ef_tests/src/cases/sanity_blocks.rs
+++ b/testing/ef_tests/src/cases/sanity_blocks.rs
@@ -67,7 +67,7 @@ impl<E: EthSpec> Case for SanityBlocks<E> {
         let spec = &testing_spec::<E>(fork_name);
 
         // Processing requires the epoch cache.
-        bulk_state.build_all_caches(spec).unwrap();
+        bulk_state.build_caches(spec).unwrap();
 
         // Spawning a second state to call the VerifyIndiviual strategy to avoid bitrot.
         // See https://github.com/sigp/lighthouse/issues/742.
diff --git a/testing/ef_tests/src/cases/sanity_slots.rs b/testing/ef_tests/src/cases/sanity_slots.rs
index a38a8930a..dd385d13f 100644
--- a/testing/ef_tests/src/cases/sanity_slots.rs
+++ b/testing/ef_tests/src/cases/sanity_slots.rs
@@ -61,7 +61,7 @@ impl<E: EthSpec> Case for SanitySlots<E> {
         let spec = &testing_spec::<E>(fork_name);
 
         // Processing requires the epoch cache.
-        state.build_all_caches(spec).unwrap();
+        state.build_caches(spec).unwrap();
 
         let mut result = (0..self.slots)
             .try_for_each(|_| per_slot_processing(&mut state, None, spec).map(|_| ()))