diff --git a/Cargo.lock b/Cargo.lock
index cb51cac30..611cdf57a 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -2442,6 +2442,7 @@ dependencies = [
  "lighthouse_network",
  "lighthouse_version",
  "network",
+ "parking_lot",
  "safe_arith",
  "sensitive_url",
  "serde",
diff --git a/beacon_node/http_api/Cargo.toml b/beacon_node/http_api/Cargo.toml
index 62373b464..315dbb9e5 100644
--- a/beacon_node/http_api/Cargo.toml
+++ b/beacon_node/http_api/Cargo.toml
@@ -27,8 +27,10 @@ slot_clock = { path = "../../common/slot_clock" }
 eth2_ssz = "0.4.1"
 bs58 = "0.4.0"
 futures = "0.3.8"
+parking_lot = "0.11.0"
 safe_arith = {path = "../../consensus/safe_arith"}
 
+
 [dev-dependencies]
 store = { path = "../store" }
 environment = { path = "../../lighthouse/environment" }
diff --git a/beacon_node/http_api/src/block_packing_efficiency.rs b/beacon_node/http_api/src/block_packing_efficiency.rs
new file mode 100644
index 000000000..d948c0d7d
--- /dev/null
+++ b/beacon_node/http_api/src/block_packing_efficiency.rs
@@ -0,0 +1,382 @@
+use beacon_chain::{BeaconChain, BeaconChainError, BeaconChainTypes};
+use eth2::lighthouse::{
+    BlockPackingEfficiency, BlockPackingEfficiencyQuery, ProposerInfo, UniqueAttestation,
+};
+use parking_lot::Mutex;
+use state_processing::{
+    per_epoch_processing::EpochProcessingSummary, BlockReplayError, BlockReplayer,
+};
+use std::collections::{HashMap, HashSet};
+use std::marker::PhantomData;
+use std::sync::Arc;
+use types::{
+    BeaconCommittee, BeaconState, BeaconStateError, ChainSpec, Epoch, EthSpec, Hash256,
+    OwnedBeaconCommittee, RelativeEpoch, SignedBeaconBlock, Slot,
+};
+use warp_utils::reject::{beacon_chain_error, custom_bad_request, custom_server_error};
+
+/// Load blocks from block roots in chunks to reduce load on memory.
+const BLOCK_ROOT_CHUNK_SIZE: usize = 100;
+
+#[derive(Debug)]
+enum PackingEfficiencyError {
+    BlockReplay(BlockReplayError),
+    BeaconState(BeaconStateError),
+    CommitteeStoreError(Slot),
+    InvalidAttestationError,
+}
+
+impl From<BlockReplayError> for PackingEfficiencyError {
+    fn from(e: BlockReplayError) -> Self {
+        Self::BlockReplay(e)
+    }
+}
+
+impl From<BeaconStateError> for PackingEfficiencyError {
+    fn from(e: BeaconStateError) -> Self {
+        Self::BeaconState(e)
+    }
+}
+
+struct CommitteeStore {
+    current_epoch_committees: Vec<OwnedBeaconCommittee>,
+    previous_epoch_committees: Vec<OwnedBeaconCommittee>,
+}
+
+impl CommitteeStore {
+    fn new() -> Self {
+        CommitteeStore {
+            current_epoch_committees: Vec::new(),
+            previous_epoch_committees: Vec::new(),
+        }
+    }
+}
+
+struct PackingEfficiencyHandler<T: EthSpec> {
+    current_slot: Slot,
+    current_epoch: Epoch,
+    prior_skip_slots: u64,
+    available_attestations: HashSet<UniqueAttestation>,
+    included_attestations: HashMap<UniqueAttestation, u64>,
+    committee_store: CommitteeStore,
+    _phantom: PhantomData<T>,
+}
+
+impl<T: EthSpec> PackingEfficiencyHandler<T> {
+    fn new(
+        start_epoch: Epoch,
+        starting_state: BeaconState<T>,
+        spec: &ChainSpec,
+    ) -> Result<Self, PackingEfficiencyError> {
+        let mut handler = PackingEfficiencyHandler {
+            current_slot: start_epoch.start_slot(T::slots_per_epoch()),
+            current_epoch: start_epoch,
+            prior_skip_slots: 0,
+            available_attestations: HashSet::new(),
+            included_attestations: HashMap::new(),
+            committee_store: CommitteeStore::new(),
+            _phantom: PhantomData::default(),
+        };
+
+        handler.compute_epoch(start_epoch, &starting_state, spec)?;
+        Ok(handler)
+    }
+
+    fn update_slot(&mut self, slot: Slot) {
+        self.current_slot = slot;
+        if slot % T::slots_per_epoch() == 0 {
+            self.current_epoch = Epoch::new(slot.as_u64() / T::slots_per_epoch());
+        }
+    }
+
+    fn prune_included_attestations(&mut self) {
+        let epoch = self.current_epoch;
+        self.included_attestations.retain(|x, _| {
+            x.slot >= Epoch::new(epoch.as_u64().saturating_sub(2)).start_slot(T::slots_per_epoch())
+        });
+    }
+
+    fn prune_available_attestations(&mut self) {
+        let slot = self.current_slot;
+        self.available_attestations
+            .retain(|x| x.slot >= (slot.as_u64().saturating_sub(T::slots_per_epoch())));
+    }
+
+    fn apply_block(
+        &mut self,
+        block: &SignedBeaconBlock<T>,
+    ) -> Result<usize, PackingEfficiencyError> {
+        let block_body = block.message().body();
+        let attestations = block_body.attestations();
+
+        let mut attestations_in_block = HashMap::new();
+        for attestation in attestations.iter() {
+            for (position, voted) in attestation.aggregation_bits.iter().enumerate() {
+                if voted {
+                    let unique_attestation = UniqueAttestation {
+                        slot: attestation.data.slot,
+                        committee_index: attestation.data.index,
+                        committee_position: position,
+                    };
+                    let inclusion_distance: u64 = block
+                        .slot()
+                        .as_u64()
+                        .checked_sub(attestation.data.slot.as_u64())
+                        .ok_or(PackingEfficiencyError::InvalidAttestationError)?;
+
+                    self.available_attestations.remove(&unique_attestation);
+                    attestations_in_block.insert(unique_attestation, inclusion_distance);
+                }
+            }
+        }
+
+        // Remove duplicate attestations as these yield no reward.
+        attestations_in_block.retain(|x, _| self.included_attestations.get(x).is_none());
+        self.included_attestations
+            .extend(attestations_in_block.clone());
+
+        Ok(attestations_in_block.len())
+    }
+
+    fn add_attestations(&mut self, slot: Slot) -> Result<(), PackingEfficiencyError> {
+        let committees = self.get_committees_at_slot(slot)?;
+        for committee in committees {
+            for position in 0..committee.committee.len() {
+                let unique_attestation = UniqueAttestation {
+                    slot,
+                    committee_index: committee.index,
+                    committee_position: position,
+                };
+                self.available_attestations.insert(unique_attestation);
+            }
+        }
+
+        Ok(())
+    }
+
+    fn compute_epoch(
+        &mut self,
+        epoch: Epoch,
+        state: &BeaconState<T>,
+        spec: &ChainSpec,
+    ) -> Result<(), PackingEfficiencyError> {
+        // Free some memory by pruning old attestations from the included set.
+        self.prune_included_attestations();
+
+        let new_committees = if state.committee_cache_is_initialized(RelativeEpoch::Current) {
+            state
+                .get_beacon_committees_at_epoch(RelativeEpoch::Current)?
+                .into_iter()
+                .map(BeaconCommittee::into_owned)
+                .collect::<Vec<_>>()
+        } else {
+            state
+                .initialize_committee_cache(epoch, spec)?
+                .get_all_beacon_committees()?
+                .into_iter()
+                .map(BeaconCommittee::into_owned)
+                .collect::<Vec<_>>()
+        };
+
+        self.committee_store.previous_epoch_committees =
+            self.committee_store.current_epoch_committees.clone();
+
+        self.committee_store.current_epoch_committees = new_committees;
+
+        Ok(())
+    }
+
+    fn get_committees_at_slot(
+        &self,
+        slot: Slot,
+    ) -> Result<Vec<OwnedBeaconCommittee>, PackingEfficiencyError> {
+        let mut committees = Vec::new();
+
+        for committee in &self.committee_store.current_epoch_committees {
+            if committee.slot == slot {
+                committees.push(committee.clone());
+            }
+        }
+        for committee in &self.committee_store.previous_epoch_committees {
+            if committee.slot == slot {
+                committees.push(committee.clone());
+            }
+        }
+
+        if committees.is_empty() {
+            return Err(PackingEfficiencyError::CommitteeStoreError(slot));
+        }
+
+        Ok(committees)
+    }
+}
+
+pub fn get_block_packing_efficiency<T: BeaconChainTypes>(
+    query: BlockPackingEfficiencyQuery,
+    chain: Arc<BeaconChain<T>>,
+) -> Result<Vec<BlockPackingEfficiency>, warp::Rejection> {
+    let spec = &chain.spec;
+
+    let start_epoch = query.start_epoch;
+    let start_slot = start_epoch.start_slot(T::EthSpec::slots_per_epoch());
+    let prior_slot = start_slot - 1;
+
+    let end_epoch = query.end_epoch;
+    let end_slot = end_epoch.end_slot(T::EthSpec::slots_per_epoch());
+
+    // Check query is valid.
+    if start_epoch > end_epoch || start_epoch == 0 {
+        return Err(custom_bad_request(format!(
+            "invalid start and end epochs: {}, {}",
+            start_epoch, end_epoch
+        )));
+    }
+
+    let prior_epoch = start_epoch - 1;
+    let start_slot_of_prior_epoch = prior_epoch.start_slot(T::EthSpec::slots_per_epoch());
+
+    // Load block roots.
+    let mut block_roots: Vec<Hash256> = chain
+        .forwards_iter_block_roots_until(start_slot_of_prior_epoch, end_slot)
+        .map_err(beacon_chain_error)?
+        .collect::<Result<Vec<(Hash256, Slot)>, _>>()
+        .map_err(beacon_chain_error)?
+        .iter()
+        .map(|(root, _)| *root)
+        .collect();
+    block_roots.dedup();
+
+    let first_block_root = block_roots
+        .first()
+        .ok_or_else(|| custom_server_error("no blocks were loaded".to_string()))?;
+
+    let first_block = chain
+        .get_block(first_block_root)
+        .and_then(|maybe_block| {
+            maybe_block.ok_or(BeaconChainError::MissingBeaconBlock(*first_block_root))
+        })
+        .map_err(beacon_chain_error)?;
+
+    // Load state for block replay.
+    let starting_state_root = first_block.state_root();
+
+    let starting_state = chain
+        .get_state(&starting_state_root, Some(prior_slot))
+        .and_then(|maybe_state| {
+            maybe_state.ok_or(BeaconChainError::MissingBeaconState(starting_state_root))
+        })
+        .map_err(beacon_chain_error)?;
+
+    // Initialize response vector.
+    let mut response = Vec::new();
+
+    // Initialize handler.
+    let handler = Arc::new(Mutex::new(
+        PackingEfficiencyHandler::new(prior_epoch, starting_state.clone(), spec)
+            .map_err(|e| custom_server_error(format!("{:?}", e)))?,
+    ));
+
+    let pre_slot_hook =
+        |state: &mut BeaconState<T::EthSpec>| -> Result<(), PackingEfficiencyError> {
+            // Add attestations to `available_attestations`.
+            handler.lock().add_attestations(state.slot())?;
+            Ok(())
+        };
+
+    let post_slot_hook = |state: &mut BeaconState<T::EthSpec>,
+                          _summary: Option<EpochProcessingSummary<T::EthSpec>>,
+                          is_skip_slot: bool|
+     -> Result<(), PackingEfficiencyError> {
+        handler.lock().update_slot(state.slot());
+
+        // Check if this a new epoch.
+        if state.slot() % T::EthSpec::slots_per_epoch() == 0 {
+            handler.lock().compute_epoch(
+                state.slot().epoch(T::EthSpec::slots_per_epoch()),
+                state,
+                spec,
+            )?;
+        }
+
+        if is_skip_slot {
+            handler.lock().prior_skip_slots += 1;
+        }
+
+        // Remove expired attestations.
+        handler.lock().prune_available_attestations();
+
+        Ok(())
+    };
+
+    let pre_block_hook = |_state: &mut BeaconState<T::EthSpec>,
+                          block: &SignedBeaconBlock<T::EthSpec>|
+     -> Result<(), PackingEfficiencyError> {
+        let slot = block.slot();
+
+        let block_message = block.message();
+        // Get block proposer info.
+        let proposer_info = ProposerInfo {
+            validator_index: block_message.proposer_index(),
+            graffiti: block_message.body().graffiti().as_utf8_lossy(),
+        };
+
+        // Store the count of available attestations at this point.
+        // In the future it may be desirable to check that the number of available attestations
+        // does not exceed the maximum possible amount given the length of available committees.
+        let available_count = handler.lock().available_attestations.len();
+
+        // Get all attestations included in the block.
+        let included = handler.lock().apply_block(block)?;
+
+        let efficiency = BlockPackingEfficiency {
+            slot,
+            block_hash: block.canonical_root(),
+            proposer_info,
+            available_attestations: available_count,
+            included_attestations: included,
+            prior_skip_slots: handler.lock().prior_skip_slots,
+        };
+
+        // Write to response.
+        if slot >= start_slot {
+            response.push(efficiency);
+        }
+
+        handler.lock().prior_skip_slots = 0;
+
+        Ok(())
+    };
+
+    // Build BlockReplayer.
+    let mut replayer = BlockReplayer::new(starting_state, spec)
+        .no_state_root_iter()
+        .no_signature_verification()
+        .minimal_block_root_verification()
+        .pre_slot_hook(Box::new(pre_slot_hook))
+        .post_slot_hook(Box::new(post_slot_hook))
+        .pre_block_hook(Box::new(pre_block_hook));
+
+    // Iterate through the block roots, loading blocks in chunks to reduce load on memory.
+    for block_root_chunks in block_roots.chunks(BLOCK_ROOT_CHUNK_SIZE) {
+        // Load blocks from the block root chunks.
+        let blocks = block_root_chunks
+            .iter()
+            .map(|root| {
+                chain
+                    .get_block(root)
+                    .and_then(|maybe_block| {
+                        maybe_block.ok_or(BeaconChainError::MissingBeaconBlock(*root))
+                    })
+                    .map_err(beacon_chain_error)
+            })
+            .collect::<Result<Vec<SignedBeaconBlock<T::EthSpec>>, _>>()?;
+
+        replayer = replayer
+            .apply_blocks(blocks, None)
+            .map_err(|e: PackingEfficiencyError| custom_server_error(format!("{:?}", e)))?;
+    }
+
+    drop(replayer);
+
+    Ok(response)
+}
diff --git a/beacon_node/http_api/src/lib.rs b/beacon_node/http_api/src/lib.rs
index 5ef845858..dcc6528a9 100644
--- a/beacon_node/http_api/src/lib.rs
+++ b/beacon_node/http_api/src/lib.rs
@@ -8,6 +8,7 @@
 mod attestation_performance;
 mod attester_duties;
 mod block_id;
+mod block_packing_efficiency;
 mod block_rewards;
 mod database;
 mod metrics;
@@ -2615,6 +2616,19 @@ pub fn serve<T: BeaconChainTypes>(
             })
         });
 
+    // GET lighthouse/analysis/block_packing_efficiency
+    let get_lighthouse_block_packing_efficiency = warp::path("lighthouse")
+        .and(warp::path("analysis"))
+        .and(warp::path("block_packing_efficiency"))
+        .and(warp::query::<eth2::lighthouse::BlockPackingEfficiencyQuery>())
+        .and(warp::path::end())
+        .and(chain_filter.clone())
+        .and_then(|query, chain: Arc<BeaconChain<T>>| {
+            blocking_json_task(move || {
+                block_packing_efficiency::get_block_packing_efficiency(query, chain)
+            })
+        });
+
     let get_events = eth1_v1
         .and(warp::path("events"))
         .and(warp::path::end())
@@ -2741,6 +2755,7 @@ pub fn serve<T: BeaconChainTypes>(
                 .or(get_lighthouse_database_info.boxed())
                 .or(get_lighthouse_block_rewards.boxed())
                 .or(get_lighthouse_attestation_performance.boxed())
+                .or(get_lighthouse_block_packing_efficiency.boxed())
                 .or(get_events.boxed()),
         )
         .or(warp::post().and(
diff --git a/common/eth2/src/lighthouse.rs b/common/eth2/src/lighthouse.rs
index adf73d8b9..a2e4a66c4 100644
--- a/common/eth2/src/lighthouse.rs
+++ b/common/eth2/src/lighthouse.rs
@@ -1,6 +1,7 @@
 //! This module contains endpoints that are non-standard and only available on Lighthouse servers.
 
 mod attestation_performance;
+mod block_packing_efficiency;
 mod block_rewards;
 
 use crate::{
@@ -18,6 +19,9 @@ use store::{AnchorInfo, Split};
 pub use attestation_performance::{
     AttestationPerformance, AttestationPerformanceQuery, AttestationPerformanceStatistics,
 };
+pub use block_packing_efficiency::{
+    BlockPackingEfficiency, BlockPackingEfficiencyQuery, ProposerInfo, UniqueAttestation,
+};
 pub use block_rewards::{AttestationRewards, BlockReward, BlockRewardMeta, BlockRewardsQuery};
 pub use lighthouse_network::{types::SyncState, PeerInfo};
 
diff --git a/common/eth2/src/lighthouse/block_packing_efficiency.rs b/common/eth2/src/lighthouse/block_packing_efficiency.rs
new file mode 100644
index 000000000..0ad6f4603
--- /dev/null
+++ b/common/eth2/src/lighthouse/block_packing_efficiency.rs
@@ -0,0 +1,34 @@
+use serde::{Deserialize, Serialize};
+use types::{Epoch, Hash256, Slot};
+
+type CommitteePosition = usize;
+type Committee = u64;
+type ValidatorIndex = u64;
+
+#[derive(Debug, Default, PartialEq, Eq, Hash, Clone, Serialize, Deserialize)]
+pub struct UniqueAttestation {
+    pub slot: Slot,
+    pub committee_index: Committee,
+    pub committee_position: CommitteePosition,
+}
+#[derive(Debug, Default, PartialEq, Clone, Serialize, Deserialize)]
+pub struct ProposerInfo {
+    pub validator_index: ValidatorIndex,
+    pub graffiti: String,
+}
+
+#[derive(Debug, Default, PartialEq, Clone, Serialize, Deserialize)]
+pub struct BlockPackingEfficiency {
+    pub slot: Slot,
+    pub block_hash: Hash256,
+    pub proposer_info: ProposerInfo,
+    pub available_attestations: usize,
+    pub included_attestations: usize,
+    pub prior_skip_slots: u64,
+}
+
+#[derive(Debug, Default, PartialEq, Clone, Serialize, Deserialize)]
+pub struct BlockPackingEfficiencyQuery {
+    pub start_epoch: Epoch,
+    pub end_epoch: Epoch,
+}