diff --git a/beacon_node/beacon_chain/src/beacon_chain.rs b/beacon_node/beacon_chain/src/beacon_chain.rs
index 41a718655..2bbb6901c 100644
--- a/beacon_node/beacon_chain/src/beacon_chain.rs
+++ b/beacon_node/beacon_chain/src/beacon_chain.rs
@@ -83,30 +83,31 @@ impl BlockProcessingOutcome {
     }
 }
 
-pub struct BeaconChain<T: ClientDB + Sized, U: SlotClock, F: ForkChoice> {
+pub struct BeaconChain<T: ClientDB + Sized, U: SlotClock, F: ForkChoice, B: BeaconStateTypes> {
     pub block_store: Arc<BeaconBlockStore<T>>,
     pub state_store: Arc<BeaconStateStore<T>>,
     pub slot_clock: U,
-    pub op_pool: OperationPool,
-    canonical_head: RwLock<CheckPoint>,
-    finalized_head: RwLock<CheckPoint>,
-    pub state: RwLock<BeaconState>,
+    pub op_pool: OperationPool<B>,
+    canonical_head: RwLock<CheckPoint<B>>,
+    finalized_head: RwLock<CheckPoint<B>>,
+    pub state: RwLock<BeaconState<B>>,
     pub spec: ChainSpec,
     pub fork_choice: RwLock<F>,
 }
 
-impl<T, U, F> BeaconChain<T, U, F>
+impl<T, U, F, B> BeaconChain<T, U, F, B>
 where
     T: ClientDB,
     U: SlotClock,
     F: ForkChoice,
+    B: BeaconStateTypes,
 {
     /// Instantiate a new Beacon Chain, from genesis.
     pub fn from_genesis(
         state_store: Arc<BeaconStateStore<T>>,
         block_store: Arc<BeaconBlockStore<T>>,
         slot_clock: U,
-        mut genesis_state: BeaconState,
+        mut genesis_state: BeaconState<B>,
         genesis_block: BeaconBlock,
         spec: ChainSpec,
         fork_choice: F,
@@ -218,7 +219,7 @@ where
             //
             // If we get `SlotOutOfBounds` error, load the oldest available historic
             // state from the DB.
-            match state.get_block_root(slot, spec) {
+            match state.get_block_root(slot) {
                 Ok(root) => {
                     if slot < earliest_slot {
                         break;
@@ -230,9 +231,9 @@ where
                 Err(BeaconStateError::SlotOutOfBounds) => {
                     // Read the earliest historic state in the current slot.
                     let earliest_historic_slot =
-                        state.slot - Slot::from(spec.slots_per_historical_root);
+                        state.slot - Slot::from(B::SlotsPerHistoricalRoot::to_usize());
                     // Load the earlier state from disk.
-                    let new_state_root = state.get_state_root(earliest_historic_slot, spec)?;
+                    let new_state_root = state.get_state_root(earliest_historic_slot)?;
 
                     // Break if the DB is unable to load the state.
                     state = match self.state_store.get_deserialized(&new_state_root) {
@@ -270,7 +271,7 @@ where
         &self,
         new_beacon_block: BeaconBlock,
         new_beacon_block_root: Hash256,
-        new_beacon_state: BeaconState,
+        new_beacon_state: BeaconState<B>,
         new_beacon_state_root: Hash256,
     ) {
         debug!(
@@ -292,7 +293,7 @@ where
     /// It is important to note that the `beacon_state` returned may not match the present slot. It
     /// is the state as it was when the head block was received, which could be some slots prior to
     /// now.
-    pub fn head(&self) -> RwLockReadGuard<CheckPoint> {
+    pub fn head(&self) -> RwLockReadGuard<CheckPoint<B>> {
         self.canonical_head.read()
     }
 
@@ -302,7 +303,7 @@ where
     /// state and calling `catchup_state` as it will not result in an old state being installed and
     /// then having it iteratively updated -- in such a case it's possible for another thread to
     /// find the state at an old slot.
-    pub fn update_state(&self, mut state: BeaconState) -> Result<(), Error> {
+    pub fn update_state(&self, mut state: BeaconState<B>) -> Result<(), Error> {
         let present_slot = match self.slot_clock.present_slot() {
             Ok(Some(slot)) => slot,
             _ => return Err(Error::UnableToReadSlot),
@@ -357,7 +358,7 @@ where
         &self,
         new_beacon_block: BeaconBlock,
         new_beacon_block_root: Hash256,
-        new_beacon_state: BeaconState,
+        new_beacon_state: BeaconState<B>,
         new_beacon_state_root: Hash256,
     ) {
         let mut finalized_head = self.finalized_head.write();
@@ -371,7 +372,7 @@ where
 
     /// Returns a read-lock guarded `CheckPoint` struct for reading the justified head (as chosen,
     /// indirectly,  by the fork-choice rule).
-    pub fn finalized_head(&self) -> RwLockReadGuard<CheckPoint> {
+    pub fn finalized_head(&self) -> RwLockReadGuard<CheckPoint<B>> {
         self.finalized_head.read()
     }
 
@@ -493,17 +494,14 @@ where
             } else {
                 // If the current head block is not from this slot, use the slot from the previous
                 // epoch.
-                *self.state.read().get_block_root(
-                    current_epoch_start_slot - self.spec.slots_per_epoch,
-                    &self.spec,
-                )?
+                *self
+                    .state
+                    .read()
+                    .get_block_root(current_epoch_start_slot - self.spec.slots_per_epoch)?
             }
         } else {
             // If we're not on the first slot of the epoch.
-            *self
-                .state
-                .read()
-                .get_block_root(current_epoch_start_slot, &self.spec)?
+            *self.state.read().get_block_root(current_epoch_start_slot)?
         };
 
         Ok(AttestationData {
@@ -667,7 +665,7 @@ where
     pub fn produce_block(
         &self,
         randao_reveal: Signature,
-    ) -> Result<(BeaconBlock, BeaconState), BlockProductionError> {
+    ) -> Result<(BeaconBlock, BeaconState<B>), BlockProductionError> {
         debug!("Producing block at slot {}...", self.state.read().slot);
 
         let mut state = self.state.read().clone();
@@ -677,7 +675,7 @@ where
         trace!("Finding attestations for new block...");
 
         let previous_block_root = *state
-            .get_block_root(state.slot - 1, &self.spec)
+            .get_block_root(state.slot - 1)
             .map_err(|_| BlockProductionError::UnableToGetBlockRootFromState)?;
 
         let (proposer_slashings, attester_slashings) =
@@ -762,7 +760,7 @@ where
     ///
     /// This could be a very expensive operation and should only be done in testing/analysis
     /// activities.
-    pub fn chain_dump(&self) -> Result<Vec<CheckPoint>, Error> {
+    pub fn chain_dump(&self) -> Result<Vec<CheckPoint<B>>, Error> {
         let mut dump = vec![];
 
         let mut last_slot = CheckPoint {
diff --git a/beacon_node/beacon_chain/src/checkpoint.rs b/beacon_node/beacon_chain/src/checkpoint.rs
index 78227e5c8..c3757949f 100644
--- a/beacon_node/beacon_chain/src/checkpoint.rs
+++ b/beacon_node/beacon_chain/src/checkpoint.rs
@@ -1,22 +1,22 @@
 use serde_derive::Serialize;
-use types::{BeaconBlock, BeaconState, Hash256};
+use types::{BeaconBlock, BeaconState, BeaconStateTypes, Hash256};
 
 /// Represents some block and it's associated state. Generally, this will be used for tracking the
 /// head, justified head and finalized head.
 #[derive(Clone, Serialize, PartialEq, Debug)]
-pub struct CheckPoint {
+pub struct CheckPoint<B: BeaconStateTypes> {
     pub beacon_block: BeaconBlock,
     pub beacon_block_root: Hash256,
-    pub beacon_state: BeaconState,
+    pub beacon_state: BeaconState<B>,
     pub beacon_state_root: Hash256,
 }
 
-impl CheckPoint {
+impl<B: BeaconStateTypes> CheckPoint<B> {
     /// Create a new checkpoint.
     pub fn new(
         beacon_block: BeaconBlock,
         beacon_block_root: Hash256,
-        beacon_state: BeaconState,
+        beacon_state: BeaconState<B>,
         beacon_state_root: Hash256,
     ) -> Self {
         Self {
@@ -32,7 +32,7 @@ impl CheckPoint {
         &mut self,
         beacon_block: BeaconBlock,
         beacon_block_root: Hash256,
-        beacon_state: BeaconState,
+        beacon_state: BeaconState<B>,
         beacon_state_root: Hash256,
     ) {
         self.beacon_block = beacon_block;
diff --git a/beacon_node/beacon_chain/src/initialise.rs b/beacon_node/beacon_chain/src/initialise.rs
index c66dd63b1..284393c02 100644
--- a/beacon_node/beacon_chain/src/initialise.rs
+++ b/beacon_node/beacon_chain/src/initialise.rs
@@ -11,14 +11,21 @@ use std::path::PathBuf;
 use std::sync::Arc;
 use tree_hash::TreeHash;
 use types::test_utils::TestingBeaconStateBuilder;
-use types::{BeaconBlock, ChainSpec, Hash256};
+use types::{BeaconBlock, ChainSpec, FewValidatorsStateTypes, FoundationStateTypes, Hash256};
 
 //TODO: Correct this for prod
 //TODO: Account for historical db
 pub fn initialise_beacon_chain(
     spec: &ChainSpec,
     db_name: Option<&PathBuf>,
-) -> Arc<BeaconChain<DiskDB, SystemTimeSlotClock, BitwiseLMDGhost<DiskDB>>> {
+) -> Arc<
+    BeaconChain<
+        DiskDB,
+        SystemTimeSlotClock,
+        BitwiseLMDGhost<DiskDB, FoundationStateTypes>,
+        FoundationStateTypes,
+    >,
+> {
     // set up the db
     let db = Arc::new(DiskDB::open(
         db_name.expect("Database directory must be included"),
@@ -64,7 +71,14 @@ pub fn initialise_beacon_chain(
 pub fn initialise_test_beacon_chain(
     spec: &ChainSpec,
     _db_name: Option<&PathBuf>,
-) -> Arc<BeaconChain<MemoryDB, SystemTimeSlotClock, BitwiseLMDGhost<MemoryDB>>> {
+) -> Arc<
+    BeaconChain<
+        MemoryDB,
+        SystemTimeSlotClock,
+        BitwiseLMDGhost<MemoryDB, FewValidatorsStateTypes>,
+        FewValidatorsStateTypes,
+    >,
+> {
     let db = Arc::new(MemoryDB::open());
     let block_store = Arc::new(BeaconBlockStore::new(db.clone()));
     let state_store = Arc::new(BeaconStateStore::new(db.clone()));
diff --git a/beacon_node/beacon_chain/src/test_utils/testing_beacon_chain_builder.rs b/beacon_node/beacon_chain/src/test_utils/testing_beacon_chain_builder.rs
index d174670c0..9f9838ae7 100644
--- a/beacon_node/beacon_chain/src/test_utils/testing_beacon_chain_builder.rs
+++ b/beacon_node/beacon_chain/src/test_utils/testing_beacon_chain_builder.rs
@@ -7,17 +7,18 @@ use fork_choice::BitwiseLMDGhost;
 use slot_clock::TestingSlotClock;
 use std::sync::Arc;
 use tree_hash::TreeHash;
-use types::test_utils::TestingBeaconStateBuilder;
 use types::*;
+use types::{test_utils::TestingBeaconStateBuilder, BeaconStateTypes, FewValidatorsStateTypes};
 
-type TestingBeaconChain = BeaconChain<MemoryDB, TestingSlotClock, BitwiseLMDGhost<MemoryDB>>;
+type TestingBeaconChain<B> =
+    BeaconChain<MemoryDB, TestingSlotClock, BitwiseLMDGhost<MemoryDB, FewValidatorsStateTypes>, B>;
 
-pub struct TestingBeaconChainBuilder {
-    state_builder: TestingBeaconStateBuilder,
+pub struct TestingBeaconChainBuilder<B: BeaconStateTypes> {
+    state_builder: TestingBeaconStateBuilder<B>,
 }
 
-impl TestingBeaconChainBuilder {
-    pub fn build(self, spec: &ChainSpec) -> TestingBeaconChain {
+impl<B: BeaconStateTypes> TestingBeaconChainBuilder<B> {
+    pub fn build(self, spec: &ChainSpec) -> TestingBeaconChain<B> {
         let db = Arc::new(MemoryDB::open());
         let block_store = Arc::new(BeaconBlockStore::new(db.clone()));
         let state_store = Arc::new(BeaconStateStore::new(db.clone()));
@@ -43,8 +44,8 @@ impl TestingBeaconChainBuilder {
     }
 }
 
-impl From<TestingBeaconStateBuilder> for TestingBeaconChainBuilder {
-    fn from(state_builder: TestingBeaconStateBuilder) -> TestingBeaconChainBuilder {
+impl<B: BeaconStateTypes> From<TestingBeaconStateBuilder<B>> for TestingBeaconChainBuilder<B> {
+    fn from(state_builder: TestingBeaconStateBuilder<B>) -> TestingBeaconChainBuilder<B> {
         TestingBeaconChainBuilder { state_builder }
     }
 }
diff --git a/eth2/fork_choice/src/bitwise_lmd_ghost.rs b/eth2/fork_choice/src/bitwise_lmd_ghost.rs
index 8ae0251d2..66100dbc1 100644
--- a/eth2/fork_choice/src/bitwise_lmd_ghost.rs
+++ b/eth2/fork_choice/src/bitwise_lmd_ghost.rs
@@ -9,8 +9,9 @@ use db::{
 };
 use log::{debug, trace};
 use std::collections::HashMap;
+use std::marker::PhantomData;
 use std::sync::Arc;
-use types::{BeaconBlock, ChainSpec, Hash256, Slot, SlotHeight};
+use types::{BeaconBlock, BeaconState, BeaconStateTypes, ChainSpec, Hash256, Slot, SlotHeight};
 
 //TODO: Pruning - Children
 //TODO: Handle Syncing
@@ -33,7 +34,7 @@ fn power_of_2_below(x: u64) -> u64 {
 }
 
 /// Stores the necessary data structures to run the optimised bitwise lmd ghost algorithm.
-pub struct BitwiseLMDGhost<T: ClientDB + Sized> {
+pub struct BitwiseLMDGhost<T: ClientDB + Sized, B: BeaconStateTypes> {
     /// A cache of known ancestors at given heights for a specific block.
     //TODO: Consider FnvHashMap
     cache: HashMap<CacheKey<u64>, Hash256>,
@@ -50,9 +51,10 @@ pub struct BitwiseLMDGhost<T: ClientDB + Sized> {
     /// State storage access.
     state_store: Arc<BeaconStateStore<T>>,
     max_known_height: SlotHeight,
+    _phantom: PhantomData<B>,
 }
 
-impl<T> BitwiseLMDGhost<T>
+impl<T, B: BeaconStateTypes> BitwiseLMDGhost<T, B>
 where
     T: ClientDB + Sized,
 {
@@ -68,6 +70,7 @@ where
             max_known_height: SlotHeight::new(0),
             block_store,
             state_store,
+            _phantom: PhantomData,
         }
     }
 
@@ -85,7 +88,7 @@ where
         // build a hashmap of block_hash to weighted votes
         let mut latest_votes: HashMap<Hash256, u64> = HashMap::new();
         // gets the current weighted votes
-        let current_state = self
+        let current_state: BeaconState<B> = self
             .state_store
             .get_deserialized(&state_root)?
             .ok_or_else(|| ForkChoiceError::MissingBeaconState(*state_root))?;
@@ -240,7 +243,7 @@ where
     }
 }
 
-impl<T: ClientDB + Sized> ForkChoice for BitwiseLMDGhost<T> {
+impl<T: ClientDB + Sized, B: BeaconStateTypes> ForkChoice for BitwiseLMDGhost<T, B> {
     fn add_block(
         &mut self,
         block: &BeaconBlock,
diff --git a/eth2/fork_choice/src/optimized_lmd_ghost.rs b/eth2/fork_choice/src/optimized_lmd_ghost.rs
index ee2919e85..3e43e2153 100644
--- a/eth2/fork_choice/src/optimized_lmd_ghost.rs
+++ b/eth2/fork_choice/src/optimized_lmd_ghost.rs
@@ -9,8 +9,9 @@ use db::{
 use log::{debug, trace};
 use std::cmp::Ordering;
 use std::collections::HashMap;
+use std::marker::PhantomData;
 use std::sync::Arc;
-use types::{BeaconBlock, ChainSpec, Hash256, Slot, SlotHeight};
+use types::{BeaconBlock, BeaconState, BeaconStateTypes, ChainSpec, Hash256, Slot, SlotHeight};
 
 //TODO: Pruning - Children
 //TODO: Handle Syncing
@@ -33,7 +34,7 @@ fn power_of_2_below(x: u64) -> u64 {
 }
 
 /// Stores the necessary data structures to run the optimised lmd ghost algorithm.
-pub struct OptimizedLMDGhost<T: ClientDB + Sized> {
+pub struct OptimizedLMDGhost<T: ClientDB + Sized, B: BeaconStateTypes> {
     /// A cache of known ancestors at given heights for a specific block.
     //TODO: Consider FnvHashMap
     cache: HashMap<CacheKey<u64>, Hash256>,
@@ -50,9 +51,10 @@ pub struct OptimizedLMDGhost<T: ClientDB + Sized> {
     /// State storage access.
     state_store: Arc<BeaconStateStore<T>>,
     max_known_height: SlotHeight,
+    _phantom: PhantomData<B>,
 }
 
-impl<T> OptimizedLMDGhost<T>
+impl<T, B: BeaconStateTypes> OptimizedLMDGhost<T, B>
 where
     T: ClientDB + Sized,
 {
@@ -68,6 +70,7 @@ where
             max_known_height: SlotHeight::new(0),
             block_store,
             state_store,
+            _phantom: PhantomData,
         }
     }
 
@@ -85,7 +88,7 @@ where
         // build a hashmap of block_hash to weighted votes
         let mut latest_votes: HashMap<Hash256, u64> = HashMap::new();
         // gets the current weighted votes
-        let current_state = self
+        let current_state: BeaconState<B> = self
             .state_store
             .get_deserialized(&state_root)?
             .ok_or_else(|| ForkChoiceError::MissingBeaconState(*state_root))?;
@@ -211,7 +214,7 @@ where
     }
 }
 
-impl<T: ClientDB + Sized> ForkChoice for OptimizedLMDGhost<T> {
+impl<T: ClientDB + Sized, B: BeaconStateTypes> ForkChoice for OptimizedLMDGhost<T, B> {
     fn add_block(
         &mut self,
         block: &BeaconBlock,
diff --git a/eth2/fork_choice/src/slow_lmd_ghost.rs b/eth2/fork_choice/src/slow_lmd_ghost.rs
index 4b236cba4..c621870d1 100644
--- a/eth2/fork_choice/src/slow_lmd_ghost.rs
+++ b/eth2/fork_choice/src/slow_lmd_ghost.rs
@@ -7,12 +7,13 @@ use db::{
 };
 use log::{debug, trace};
 use std::collections::HashMap;
+use std::marker::PhantomData;
 use std::sync::Arc;
-use types::{BeaconBlock, ChainSpec, Hash256, Slot};
+use types::{BeaconBlock, BeaconState, BeaconStateTypes, ChainSpec, Hash256, Slot};
 
 //TODO: Pruning and syncing
 
-pub struct SlowLMDGhost<T: ClientDB + Sized> {
+pub struct SlowLMDGhost<T: ClientDB + Sized, B: BeaconStateTypes> {
     /// The latest attestation targets as a map of validator index to block hash.
     //TODO: Could this be a fixed size vec
     latest_attestation_targets: HashMap<u64, Hash256>,
@@ -22,9 +23,10 @@ pub struct SlowLMDGhost<T: ClientDB + Sized> {
     block_store: Arc<BeaconBlockStore<T>>,
     /// State storage access.
     state_store: Arc<BeaconStateStore<T>>,
+    _phantom: PhantomData<B>,
 }
 
-impl<T> SlowLMDGhost<T>
+impl<T, B: BeaconStateTypes> SlowLMDGhost<T, B>
 where
     T: ClientDB + Sized,
 {
@@ -37,6 +39,7 @@ where
             children: HashMap::new(),
             block_store,
             state_store,
+            _phantom: PhantomData,
         }
     }
 
@@ -54,7 +57,7 @@ where
         // build a hashmap of block_hash to weighted votes
         let mut latest_votes: HashMap<Hash256, u64> = HashMap::new();
         // gets the current weighted votes
-        let current_state = self
+        let current_state: BeaconState<B> = self
             .state_store
             .get_deserialized(&state_root)?
             .ok_or_else(|| ForkChoiceError::MissingBeaconState(*state_root))?;
@@ -105,7 +108,7 @@ where
     }
 }
 
-impl<T: ClientDB + Sized> ForkChoice for SlowLMDGhost<T> {
+impl<T: ClientDB + Sized, B: BeaconStateTypes> ForkChoice for SlowLMDGhost<T, B> {
     /// Process when a block is added
     fn add_block(
         &mut self,
diff --git a/eth2/types/src/beacon_state/beacon_state_types.rs b/eth2/types/src/beacon_state/beacon_state_types.rs
index 4d296feed..5012ebb37 100644
--- a/eth2/types/src/beacon_state/beacon_state_types.rs
+++ b/eth2/types/src/beacon_state/beacon_state_types.rs
@@ -1,12 +1,13 @@
 use crate::*;
 use fixed_len_vec::typenum::{Unsigned, U1024, U8, U8192};
+use std::fmt::Debug;
 
-pub trait BeaconStateTypes: Default {
-    type ShardCount: Unsigned + Clone + Sync + Send;
-    type SlotsPerHistoricalRoot: Unsigned + Clone + Sync + Send;
-    type LatestRandaoMixesLength: Unsigned + Clone + Sync + Send;
-    type LatestActiveIndexRootsLength: Unsigned + Clone + Sync + Send;
-    type LatestSlashedExitLength: Unsigned + Clone + Sync + Send;
+pub trait BeaconStateTypes: Default + Sync + Send + Clone + Debug + PartialEq {
+    type ShardCount: Unsigned + Clone + Sync + Send + Debug + PartialEq;
+    type SlotsPerHistoricalRoot: Unsigned + Clone + Sync + Send + Debug + PartialEq;
+    type LatestRandaoMixesLength: Unsigned + Clone + Sync + Send + Debug + PartialEq;
+    type LatestActiveIndexRootsLength: Unsigned + Clone + Sync + Send + Debug + PartialEq;
+    type LatestSlashedExitLength: Unsigned + Clone + Sync + Send + Debug + PartialEq;
 
     fn spec() -> ChainSpec;
 }