diff --git a/eth2/types/src/attestation.rs b/eth2/types/src/attestation.rs
index f7bfdaab9..d1511763d 100644
--- a/eth2/types/src/attestation.rs
+++ b/eth2/types/src/attestation.rs
@@ -5,7 +5,7 @@ use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
 use tree_hash::TreeHash;
-use tree_hash_derive::{SignedRoot, TreeHash};
+use tree_hash_derive::{CachedTreeHash, SignedRoot, TreeHash};
 
 /// Details an attestation that can be slashable.
 ///
@@ -19,6 +19,7 @@ use tree_hash_derive::{SignedRoot, TreeHash};
     Encode,
     Decode,
     TreeHash,
+    CachedTreeHash,
     TestRandom,
     SignedRoot,
 )]
@@ -58,4 +59,5 @@ mod tests {
     use super::*;
 
     ssz_tests!(Attestation);
+    cached_tree_hash_tests!(Attestation);
 }
diff --git a/eth2/types/src/attestation_data.rs b/eth2/types/src/attestation_data.rs
index f8a0ecd15..c963d6001 100644
--- a/eth2/types/src/attestation_data.rs
+++ b/eth2/types/src/attestation_data.rs
@@ -5,7 +5,7 @@ use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
 use tree_hash::TreeHash;
-use tree_hash_derive::{SignedRoot, TreeHash};
+use tree_hash_derive::{CachedTreeHash, SignedRoot, TreeHash};
 
 /// The data upon which an attestation is based.
 ///
@@ -21,6 +21,7 @@ use tree_hash_derive::{SignedRoot, TreeHash};
     Encode,
     Decode,
     TreeHash,
+    CachedTreeHash,
     TestRandom,
     SignedRoot,
 )]
@@ -47,4 +48,5 @@ mod tests {
     use super::*;
 
     ssz_tests!(AttestationData);
+    cached_tree_hash_tests!(AttestationData);
 }
diff --git a/eth2/types/src/attestation_data_and_custody_bit.rs b/eth2/types/src/attestation_data_and_custody_bit.rs
index e5dc920dc..85a5875ab 100644
--- a/eth2/types/src/attestation_data_and_custody_bit.rs
+++ b/eth2/types/src/attestation_data_and_custody_bit.rs
@@ -3,12 +3,12 @@ use crate::test_utils::TestRandom;
 use rand::RngCore;
 use serde_derive::Serialize;
 use ssz_derive::{Decode, Encode};
-use tree_hash_derive::TreeHash;
+use tree_hash_derive::{CachedTreeHash, TreeHash};
 
 /// Used for pairing an attestation with a proof-of-custody.
 ///
 /// Spec v0.5.1
-#[derive(Debug, Clone, PartialEq, Default, Serialize, Encode, Decode, TreeHash)]
+#[derive(Debug, Clone, PartialEq, Default, Serialize, Encode, Decode, TreeHash, CachedTreeHash)]
 pub struct AttestationDataAndCustodyBit {
     pub data: AttestationData,
     pub custody_bit: bool,
@@ -28,4 +28,5 @@ mod test {
     use super::*;
 
     ssz_tests!(AttestationDataAndCustodyBit);
+    cached_tree_hash_tests!(AttestationDataAndCustodyBit);
 }
diff --git a/eth2/types/src/attester_slashing.rs b/eth2/types/src/attester_slashing.rs
index b5e851dbd..d4848b01c 100644
--- a/eth2/types/src/attester_slashing.rs
+++ b/eth2/types/src/attester_slashing.rs
@@ -3,12 +3,23 @@ use rand::RngCore;
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
-use tree_hash_derive::TreeHash;
+use tree_hash_derive::{CachedTreeHash, TreeHash};
 
 /// Two conflicting attestations.
 ///
 /// Spec v0.5.1
-#[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
+#[derive(
+    Debug,
+    PartialEq,
+    Clone,
+    Serialize,
+    Deserialize,
+    Encode,
+    Decode,
+    TreeHash,
+    CachedTreeHash,
+    TestRandom,
+)]
 pub struct AttesterSlashing {
     pub slashable_attestation_1: SlashableAttestation,
     pub slashable_attestation_2: SlashableAttestation,
@@ -19,4 +30,5 @@ mod tests {
     use super::*;
 
     ssz_tests!(AttesterSlashing);
+    cached_tree_hash_tests!(AttesterSlashing);
 }
diff --git a/eth2/types/src/beacon_block.rs b/eth2/types/src/beacon_block.rs
index b4d2752d6..d198d16fc 100644
--- a/eth2/types/src/beacon_block.rs
+++ b/eth2/types/src/beacon_block.rs
@@ -6,7 +6,7 @@ use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
 use tree_hash::TreeHash;
-use tree_hash_derive::{SignedRoot, TreeHash};
+use tree_hash_derive::{CachedTreeHash, SignedRoot, TreeHash};
 
 /// A block of the `BeaconChain`.
 ///
@@ -20,6 +20,7 @@ use tree_hash_derive::{SignedRoot, TreeHash};
     Encode,
     Decode,
     TreeHash,
+    CachedTreeHash,
     TestRandom,
     SignedRoot,
 )]
@@ -100,4 +101,5 @@ mod tests {
     use super::*;
 
     ssz_tests!(BeaconBlock);
+    cached_tree_hash_tests!(BeaconBlock);
 }
diff --git a/eth2/types/src/beacon_block_body.rs b/eth2/types/src/beacon_block_body.rs
index de4951f1f..15ba00d6b 100644
--- a/eth2/types/src/beacon_block_body.rs
+++ b/eth2/types/src/beacon_block_body.rs
@@ -4,12 +4,23 @@ use rand::RngCore;
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
-use tree_hash_derive::TreeHash;
+use tree_hash_derive::{CachedTreeHash, TreeHash};
 
 /// The body of a `BeaconChain` block, containing operations.
 ///
 /// Spec v0.5.1
-#[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
+#[derive(
+    Debug,
+    PartialEq,
+    Clone,
+    Serialize,
+    Deserialize,
+    Encode,
+    Decode,
+    TreeHash,
+    CachedTreeHash,
+    TestRandom,
+)]
 pub struct BeaconBlockBody {
     pub randao_reveal: Signature,
     pub eth1_data: Eth1Data,
@@ -26,4 +37,5 @@ mod tests {
     use super::*;
 
     ssz_tests!(BeaconBlockBody);
+    cached_tree_hash_tests!(BeaconBlockBody);
 }
diff --git a/eth2/types/src/beacon_block_header.rs b/eth2/types/src/beacon_block_header.rs
index e4db3a721..5b35da1b6 100644
--- a/eth2/types/src/beacon_block_header.rs
+++ b/eth2/types/src/beacon_block_header.rs
@@ -6,7 +6,7 @@ use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
 use tree_hash::{SignedRoot, TreeHash};
-use tree_hash_derive::{SignedRoot, TreeHash};
+use tree_hash_derive::{CachedTreeHash, SignedRoot, TreeHash};
 
 /// A header of a `BeaconBlock`.
 ///
@@ -20,6 +20,7 @@ use tree_hash_derive::{SignedRoot, TreeHash};
     Encode,
     Decode,
     TreeHash,
+    CachedTreeHash,
     TestRandom,
     SignedRoot,
 )]
@@ -59,4 +60,5 @@ mod tests {
     use super::*;
 
     ssz_tests!(BeaconBlockHeader);
+    cached_tree_hash_tests!(BeaconBlockHeader);
 }
diff --git a/eth2/types/src/beacon_state.rs b/eth2/types/src/beacon_state.rs
index eef408308..227e6a4f9 100644
--- a/eth2/types/src/beacon_state.rs
+++ b/eth2/types/src/beacon_state.rs
@@ -9,7 +9,7 @@ use ssz::{hash, ssz_encode};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
 use tree_hash::TreeHash;
-use tree_hash_derive::TreeHash;
+use tree_hash_derive::{CachedTreeHash, TreeHash};
 
 mod epoch_cache;
 mod pubkey_cache;
@@ -47,7 +47,18 @@ pub enum Error {
 /// The state of the `BeaconChain` at some slot.
 ///
 /// Spec v0.5.1
-#[derive(Debug, PartialEq, Clone, Serialize, Deserialize, TestRandom, Encode, Decode, TreeHash)]
+#[derive(
+    Debug,
+    PartialEq,
+    Clone,
+    Serialize,
+    Deserialize,
+    TestRandom,
+    Encode,
+    Decode,
+    TreeHash,
+    CachedTreeHash,
+)]
 pub struct BeaconState {
     // Misc
     pub slot: Slot,
diff --git a/eth2/types/src/beacon_state/tests.rs b/eth2/types/src/beacon_state/tests.rs
index dc16a013b..f417dd555 100644
--- a/eth2/types/src/beacon_state/tests.rs
+++ b/eth2/types/src/beacon_state/tests.rs
@@ -3,6 +3,7 @@ use super::*;
 use crate::test_utils::*;
 
 ssz_tests!(BeaconState);
+cached_tree_hash_tests!(BeaconState);
 
 /// Test that
 ///
diff --git a/eth2/types/src/crosslink.rs b/eth2/types/src/crosslink.rs
index 623226ad6..448f5ea30 100644
--- a/eth2/types/src/crosslink.rs
+++ b/eth2/types/src/crosslink.rs
@@ -4,7 +4,7 @@ use rand::RngCore;
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
-use tree_hash_derive::TreeHash;
+use tree_hash_derive::{CachedTreeHash, TreeHash};
 
 /// Specifies the block hash for a shard at an epoch.
 ///
@@ -20,6 +20,7 @@ use tree_hash_derive::TreeHash;
     Encode,
     Decode,
     TreeHash,
+    CachedTreeHash,
     TestRandom,
 )]
 pub struct Crosslink {
@@ -32,4 +33,5 @@ mod tests {
     use super::*;
 
     ssz_tests!(Crosslink);
+    cached_tree_hash_tests!(Crosslink);
 }
diff --git a/eth2/types/src/crosslink_committee.rs b/eth2/types/src/crosslink_committee.rs
index e8fc1b96d..25c42c07b 100644
--- a/eth2/types/src/crosslink_committee.rs
+++ b/eth2/types/src/crosslink_committee.rs
@@ -1,9 +1,20 @@
 use crate::*;
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
-use tree_hash_derive::TreeHash;
+use tree_hash_derive::{CachedTreeHash, TreeHash};
 
-#[derive(Default, Clone, Debug, PartialEq, Serialize, Deserialize, Decode, Encode, TreeHash)]
+#[derive(
+    Default,
+    Clone,
+    Debug,
+    PartialEq,
+    Serialize,
+    Deserialize,
+    Decode,
+    Encode,
+    TreeHash,
+    CachedTreeHash,
+)]
 pub struct CrosslinkCommittee {
     pub slot: Slot,
     pub shard: Shard,
diff --git a/eth2/types/src/deposit.rs b/eth2/types/src/deposit.rs
index 291173d34..e8d2f5a4b 100644
--- a/eth2/types/src/deposit.rs
+++ b/eth2/types/src/deposit.rs
@@ -4,12 +4,23 @@ use rand::RngCore;
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
-use tree_hash_derive::TreeHash;
+use tree_hash_derive::{CachedTreeHash, TreeHash};
 
 /// A deposit to potentially become a beacon chain validator.
 ///
 /// Spec v0.5.1
-#[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
+#[derive(
+    Debug,
+    PartialEq,
+    Clone,
+    Serialize,
+    Deserialize,
+    Encode,
+    Decode,
+    TreeHash,
+    CachedTreeHash,
+    TestRandom,
+)]
 pub struct Deposit {
     pub proof: TreeHashVector<Hash256>,
     pub index: u64,
@@ -21,4 +32,5 @@ mod tests {
     use super::*;
 
     ssz_tests!(Deposit);
+    cached_tree_hash_tests!(Deposit);
 }
diff --git a/eth2/types/src/deposit_data.rs b/eth2/types/src/deposit_data.rs
index bc96ac7c4..38c44d1a7 100644
--- a/eth2/types/src/deposit_data.rs
+++ b/eth2/types/src/deposit_data.rs
@@ -4,12 +4,23 @@ use rand::RngCore;
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
-use tree_hash_derive::TreeHash;
+use tree_hash_derive::{CachedTreeHash, TreeHash};
 
 /// Data generated by the deposit contract.
 ///
 /// Spec v0.5.1
-#[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
+#[derive(
+    Debug,
+    PartialEq,
+    Clone,
+    Serialize,
+    Deserialize,
+    Encode,
+    Decode,
+    TreeHash,
+    CachedTreeHash,
+    TestRandom,
+)]
 pub struct DepositData {
     pub amount: u64,
     pub timestamp: u64,
@@ -21,4 +32,5 @@ mod tests {
     use super::*;
 
     ssz_tests!(DepositData);
+    cached_tree_hash_tests!(DepositData);
 }
diff --git a/eth2/types/src/deposit_input.rs b/eth2/types/src/deposit_input.rs
index be2106cb4..af1049a20 100644
--- a/eth2/types/src/deposit_input.rs
+++ b/eth2/types/src/deposit_input.rs
@@ -6,7 +6,7 @@ use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
 use tree_hash::{SignedRoot, TreeHash};
-use tree_hash_derive::{SignedRoot, TreeHash};
+use tree_hash_derive::{CachedTreeHash, SignedRoot, TreeHash};
 
 /// The data supplied by the user to the deposit contract.
 ///
@@ -21,6 +21,7 @@ use tree_hash_derive::{SignedRoot, TreeHash};
     Decode,
     SignedRoot,
     TreeHash,
+    CachedTreeHash,
     TestRandom,
 )]
 pub struct DepositInput {
@@ -68,6 +69,7 @@ mod tests {
     use super::*;
 
     ssz_tests!(DepositInput);
+    cached_tree_hash_tests!(DepositInput);
 
     #[test]
     fn can_create_and_validate() {
diff --git a/eth2/types/src/eth1_data.rs b/eth2/types/src/eth1_data.rs
index 2ad460d13..3c0c3af02 100644
--- a/eth2/types/src/eth1_data.rs
+++ b/eth2/types/src/eth1_data.rs
@@ -4,13 +4,23 @@ use rand::RngCore;
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
-use tree_hash_derive::TreeHash;
+use tree_hash_derive::{CachedTreeHash, TreeHash};
 
 /// Contains data obtained from the Eth1 chain.
 ///
 /// Spec v0.5.1
 #[derive(
-    Debug, PartialEq, Clone, Default, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom,
+    Debug,
+    PartialEq,
+    Clone,
+    Default,
+    Serialize,
+    Deserialize,
+    Encode,
+    Decode,
+    TreeHash,
+    CachedTreeHash,
+    TestRandom,
 )]
 pub struct Eth1Data {
     pub deposit_root: Hash256,
@@ -22,4 +32,5 @@ mod tests {
     use super::*;
 
     ssz_tests!(Eth1Data);
+    cached_tree_hash_tests!(Eth1Data);
 }
diff --git a/eth2/types/src/eth1_data_vote.rs b/eth2/types/src/eth1_data_vote.rs
index 7a77c8ff0..00818ebf4 100644
--- a/eth2/types/src/eth1_data_vote.rs
+++ b/eth2/types/src/eth1_data_vote.rs
@@ -4,13 +4,23 @@ use rand::RngCore;
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
-use tree_hash_derive::TreeHash;
+use tree_hash_derive::{CachedTreeHash, TreeHash};
 
 /// A summation of votes for some `Eth1Data`.
 ///
 /// Spec v0.5.1
 #[derive(
-    Debug, PartialEq, Clone, Default, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom,
+    Debug,
+    PartialEq,
+    Clone,
+    Default,
+    Serialize,
+    Deserialize,
+    Encode,
+    Decode,
+    TreeHash,
+    CachedTreeHash,
+    TestRandom,
 )]
 pub struct Eth1DataVote {
     pub eth1_data: Eth1Data,
@@ -22,4 +32,5 @@ mod tests {
     use super::*;
 
     ssz_tests!(Eth1DataVote);
+    cached_tree_hash_tests!(Eth1DataVote);
 }
diff --git a/eth2/types/src/fork.rs b/eth2/types/src/fork.rs
index d99842855..83d4f5dc6 100644
--- a/eth2/types/src/fork.rs
+++ b/eth2/types/src/fork.rs
@@ -7,13 +7,23 @@ use rand::RngCore;
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
-use tree_hash_derive::TreeHash;
+use tree_hash_derive::{CachedTreeHash, TreeHash};
 
 /// Specifies a fork of the `BeaconChain`, to prevent replay attacks.
 ///
 /// Spec v0.5.1
 #[derive(
-    Debug, Clone, PartialEq, Default, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom,
+    Debug,
+    Clone,
+    PartialEq,
+    Default,
+    Serialize,
+    Deserialize,
+    Encode,
+    Decode,
+    TreeHash,
+    CachedTreeHash,
+    TestRandom,
 )]
 pub struct Fork {
     #[serde(deserialize_with = "fork_from_hex_str")]
@@ -54,6 +64,7 @@ mod tests {
     use super::*;
 
     ssz_tests!(Fork);
+    cached_tree_hash_tests!(Fork);
 
     fn test_genesis(version: u32, epoch: Epoch) {
         let mut spec = ChainSpec::foundation();
diff --git a/eth2/types/src/historical_batch.rs b/eth2/types/src/historical_batch.rs
index c4f62fcfc..13e57131a 100644
--- a/eth2/types/src/historical_batch.rs
+++ b/eth2/types/src/historical_batch.rs
@@ -4,12 +4,23 @@ use rand::RngCore;
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
-use tree_hash_derive::TreeHash;
+use tree_hash_derive::{CachedTreeHash, TreeHash};
 
 /// Historical block and state roots.
 ///
 /// Spec v0.5.1
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
+#[derive(
+    Debug,
+    Clone,
+    PartialEq,
+    Serialize,
+    Deserialize,
+    Encode,
+    Decode,
+    TreeHash,
+    CachedTreeHash,
+    TestRandom,
+)]
 pub struct HistoricalBatch {
     pub block_roots: TreeHashVector<Hash256>,
     pub state_roots: TreeHashVector<Hash256>,
@@ -20,4 +31,5 @@ mod tests {
     use super::*;
 
     ssz_tests!(HistoricalBatch);
+    cached_tree_hash_tests!(HistoricalBatch);
 }
diff --git a/eth2/types/src/pending_attestation.rs b/eth2/types/src/pending_attestation.rs
index ce9ce3d77..b71351f9a 100644
--- a/eth2/types/src/pending_attestation.rs
+++ b/eth2/types/src/pending_attestation.rs
@@ -4,12 +4,23 @@ use rand::RngCore;
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
-use tree_hash_derive::TreeHash;
+use tree_hash_derive::{CachedTreeHash, TreeHash};
 
 /// An attestation that has been included in the state but not yet fully processed.
 ///
 /// Spec v0.5.1
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
+#[derive(
+    Debug,
+    Clone,
+    PartialEq,
+    Serialize,
+    Deserialize,
+    Encode,
+    Decode,
+    TreeHash,
+    CachedTreeHash,
+    TestRandom,
+)]
 pub struct PendingAttestation {
     pub aggregation_bitfield: Bitfield,
     pub data: AttestationData,
@@ -34,4 +45,5 @@ mod tests {
     use super::*;
 
     ssz_tests!(PendingAttestation);
+    cached_tree_hash_tests!(PendingAttestation);
 }
diff --git a/eth2/types/src/proposer_slashing.rs b/eth2/types/src/proposer_slashing.rs
index a3501a5bd..bf26ae508 100644
--- a/eth2/types/src/proposer_slashing.rs
+++ b/eth2/types/src/proposer_slashing.rs
@@ -4,12 +4,23 @@ use rand::RngCore;
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
-use tree_hash_derive::TreeHash;
+use tree_hash_derive::{CachedTreeHash, TreeHash};
 
 /// Two conflicting proposals from the same proposer (validator).
 ///
 /// Spec v0.5.1
-#[derive(Debug, PartialEq, Clone, Serialize, Deserialize, Encode, Decode, TreeHash, TestRandom)]
+#[derive(
+    Debug,
+    PartialEq,
+    Clone,
+    Serialize,
+    Deserialize,
+    Encode,
+    Decode,
+    TreeHash,
+    CachedTreeHash,
+    TestRandom,
+)]
 pub struct ProposerSlashing {
     pub proposer_index: u64,
     pub header_1: BeaconBlockHeader,
@@ -21,4 +32,5 @@ mod tests {
     use super::*;
 
     ssz_tests!(ProposerSlashing);
+    cached_tree_hash_tests!(ProposerSlashing);
 }
diff --git a/eth2/types/src/slashable_attestation.rs b/eth2/types/src/slashable_attestation.rs
index 9c460e482..fb838e0c4 100644
--- a/eth2/types/src/slashable_attestation.rs
+++ b/eth2/types/src/slashable_attestation.rs
@@ -4,7 +4,7 @@ use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
 use tree_hash::TreeHash;
-use tree_hash_derive::{SignedRoot, TreeHash};
+use tree_hash_derive::{CachedTreeHash, SignedRoot, TreeHash};
 
 /// Details an attestation that can be slashable.
 ///
@@ -20,6 +20,7 @@ use tree_hash_derive::{SignedRoot, TreeHash};
     Encode,
     Decode,
     TreeHash,
+    CachedTreeHash,
     TestRandom,
     SignedRoot,
 )]
@@ -133,6 +134,7 @@ mod tests {
     }
 
     ssz_tests!(SlashableAttestation);
+    cached_tree_hash_tests!(SlashableAttestation);
 
     fn create_slashable_attestation(
         slot_factor: u64,
diff --git a/eth2/types/src/slot_epoch_macros.rs b/eth2/types/src/slot_epoch_macros.rs
index b3ca5c4bc..446838d0a 100644
--- a/eth2/types/src/slot_epoch_macros.rs
+++ b/eth2/types/src/slot_epoch_macros.rs
@@ -224,6 +224,26 @@ macro_rules! impl_ssz {
             }
         }
 
+        impl cached_tree_hash::CachedTreeHash<$type> for $type {
+            fn new_tree_hash_cache(
+                &self,
+                depth: usize,
+            ) -> Result<cached_tree_hash::TreeHashCache, cached_tree_hash::Error> {
+                self.0.new_tree_hash_cache(depth)
+            }
+
+            fn tree_hash_cache_schema(&self, depth: usize) -> cached_tree_hash::BTreeSchema {
+                self.0.tree_hash_cache_schema(depth)
+            }
+
+            fn update_tree_hash_cache(
+                &self,
+                cache: &mut cached_tree_hash::TreeHashCache,
+            ) -> Result<(), cached_tree_hash::Error> {
+                self.0.update_tree_hash_cache(cache)
+            }
+        }
+
         impl<T: RngCore> TestRandom<T> for $type {
             fn random_for_test(rng: &mut T) -> Self {
                 $type::from(u64::random_for_test(rng))
@@ -545,6 +565,7 @@ macro_rules! all_tests {
         math_between_tests!($type, $type);
         math_tests!($type);
         ssz_tests!($type);
+        cached_tree_hash_tests!($type);
 
         mod u64_tests {
             use super::*;
diff --git a/eth2/types/src/test_utils/macros.rs b/eth2/types/src/test_utils/macros.rs
index d5711e96e..5f355bfe9 100644
--- a/eth2/types/src/test_utils/macros.rs
+++ b/eth2/types/src/test_utils/macros.rs
@@ -32,3 +32,29 @@ macro_rules! ssz_tests {
         }
     };
 }
+
+#[cfg(test)]
+#[macro_export]
+macro_rules! cached_tree_hash_tests {
+    ($type: ident) => {
+        #[test]
+        pub fn test_cached_tree_hash() {
+            use crate::test_utils::{SeedableRng, TestRandom, XorShiftRng};
+            use tree_hash::TreeHash;
+
+            let mut rng = XorShiftRng::from_seed([42; 16]);
+
+            let original = $type::random_for_test(&mut rng);
+
+            let mut hasher = cached_tree_hash::CachedTreeHasher::new(&original).unwrap();
+
+            assert_eq!(hasher.tree_hash_root().unwrap(), original.tree_hash_root());
+
+            let modified = $type::random_for_test(&mut rng);
+
+            hasher.update(&modified).unwrap();
+
+            assert_eq!(hasher.tree_hash_root().unwrap(), modified.tree_hash_root());
+        }
+    };
+}
diff --git a/eth2/types/src/transfer.rs b/eth2/types/src/transfer.rs
index 82ead03d5..aea13fdd7 100644
--- a/eth2/types/src/transfer.rs
+++ b/eth2/types/src/transfer.rs
@@ -7,7 +7,7 @@ use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
 use tree_hash::TreeHash;
-use tree_hash_derive::{SignedRoot, TreeHash};
+use tree_hash_derive::{CachedTreeHash, SignedRoot, TreeHash};
 
 /// The data submitted to the deposit contract.
 ///
@@ -20,6 +20,7 @@ use tree_hash_derive::{SignedRoot, TreeHash};
     Encode,
     Decode,
     TreeHash,
+    CachedTreeHash,
     TestRandom,
     SignedRoot,
     Derivative,
@@ -42,4 +43,5 @@ mod tests {
     use super::*;
 
     ssz_tests!(Transfer);
+    cached_tree_hash_tests!(Transfer);
 }
diff --git a/eth2/types/src/tree_hash_vector.rs b/eth2/types/src/tree_hash_vector.rs
index 4b6ebad37..6279c4512 100644
--- a/eth2/types/src/tree_hash_vector.rs
+++ b/eth2/types/src/tree_hash_vector.rs
@@ -108,3 +108,25 @@ where
         Vec::random_for_test(rng).into()
     }
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use tree_hash::TreeHash;
+
+    #[test]
+    pub fn test_cached_tree_hash() {
+        let original = TreeHashVector::from(vec![1_u64, 2, 3, 4]);
+
+        let mut hasher = cached_tree_hash::CachedTreeHasher::new(&original).unwrap();
+
+        assert_eq!(hasher.tree_hash_root().unwrap(), original.tree_hash_root());
+
+        let modified = TreeHashVector::from(vec![1_u64, 1, 1, 1]);
+
+        hasher.update(&modified).unwrap();
+
+        assert_eq!(hasher.tree_hash_root().unwrap(), modified.tree_hash_root());
+    }
+
+}
diff --git a/eth2/types/src/validator.rs b/eth2/types/src/validator.rs
index bbd68ed2b..a20eb6426 100644
--- a/eth2/types/src/validator.rs
+++ b/eth2/types/src/validator.rs
@@ -3,12 +3,23 @@ use rand::RngCore;
 use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
-use tree_hash_derive::TreeHash;
+use tree_hash_derive::{CachedTreeHash, TreeHash};
 
 /// Information about a `BeaconChain` validator.
 ///
 /// Spec v0.5.1
-#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, Encode, Decode, TestRandom, TreeHash)]
+#[derive(
+    Debug,
+    Clone,
+    PartialEq,
+    Serialize,
+    Deserialize,
+    Encode,
+    Decode,
+    TestRandom,
+    TreeHash,
+    CachedTreeHash,
+)]
 pub struct Validator {
     pub pubkey: PublicKey,
     pub withdrawal_credentials: Hash256,
@@ -111,4 +122,5 @@ mod tests {
     }
 
     ssz_tests!(Validator);
+    cached_tree_hash_tests!(Validator);
 }
diff --git a/eth2/types/src/voluntary_exit.rs b/eth2/types/src/voluntary_exit.rs
index cb872cb98..8a780db75 100644
--- a/eth2/types/src/voluntary_exit.rs
+++ b/eth2/types/src/voluntary_exit.rs
@@ -5,7 +5,7 @@ use serde_derive::{Deserialize, Serialize};
 use ssz_derive::{Decode, Encode};
 use test_random_derive::TestRandom;
 use tree_hash::TreeHash;
-use tree_hash_derive::{SignedRoot, TreeHash};
+use tree_hash_derive::{CachedTreeHash, SignedRoot, TreeHash};
 
 /// An exit voluntarily submitted a validator who wishes to withdraw.
 ///
@@ -19,6 +19,7 @@ use tree_hash_derive::{SignedRoot, TreeHash};
     Encode,
     Decode,
     TreeHash,
+    CachedTreeHash,
     TestRandom,
     SignedRoot,
 )]
@@ -34,4 +35,5 @@ mod tests {
     use super::*;
 
     ssz_tests!(VoluntaryExit);
+    cached_tree_hash_tests!(VoluntaryExit);
 }
diff --git a/eth2/utils/bls/Cargo.toml b/eth2/utils/bls/Cargo.toml
index 4ce499580..dcace15c8 100644
--- a/eth2/utils/bls/Cargo.toml
+++ b/eth2/utils/bls/Cargo.toml
@@ -6,6 +6,7 @@ edition = "2018"
 
 [dependencies]
 bls-aggregates = { git = "https://github.com/sigp/signature-schemes", tag = "0.6.1" }
+cached_tree_hash = { path = "../cached_tree_hash" }
 hashing = { path = "../hashing" }
 hex = "0.3"
 serde = "1.0"
diff --git a/eth2/utils/bls/src/aggregate_signature.rs b/eth2/utils/bls/src/aggregate_signature.rs
index 0fbcc3493..e6c6cff9a 100644
--- a/eth2/utils/bls/src/aggregate_signature.rs
+++ b/eth2/utils/bls/src/aggregate_signature.rs
@@ -2,6 +2,7 @@ use super::{AggregatePublicKey, Signature, BLS_AGG_SIG_BYTE_SIZE};
 use bls_aggregates::{
     AggregatePublicKey as RawAggregatePublicKey, AggregateSignature as RawAggregateSignature,
 };
+use cached_tree_hash::cached_tree_hash_ssz_encoding_as_vector;
 use serde::de::{Deserialize, Deserializer};
 use serde::ser::{Serialize, Serializer};
 use serde_hex::{encode as hex_encode, HexVisitor};
@@ -167,6 +168,7 @@ impl<'de> Deserialize<'de> for AggregateSignature {
 }
 
 tree_hash_ssz_encoding_as_vector!(AggregateSignature);
+cached_tree_hash_ssz_encoding_as_vector!(AggregateSignature, 96);
 
 #[cfg(test)]
 mod tests {
diff --git a/eth2/utils/bls/src/fake_aggregate_signature.rs b/eth2/utils/bls/src/fake_aggregate_signature.rs
index f201eba3e..aeb89507d 100644
--- a/eth2/utils/bls/src/fake_aggregate_signature.rs
+++ b/eth2/utils/bls/src/fake_aggregate_signature.rs
@@ -1,4 +1,5 @@
 use super::{fake_signature::FakeSignature, AggregatePublicKey, BLS_AGG_SIG_BYTE_SIZE};
+use cached_tree_hash::cached_tree_hash_ssz_encoding_as_vector;
 use serde::de::{Deserialize, Deserializer};
 use serde::ser::{Serialize, Serializer};
 use serde_hex::{encode as hex_encode, PrefixedHexVisitor};
@@ -100,6 +101,7 @@ impl<'de> Deserialize<'de> for FakeAggregateSignature {
 }
 
 tree_hash_ssz_encoding_as_vector!(FakeAggregateSignature);
+cached_tree_hash_ssz_encoding_as_vector!(FakeAggregateSignature, 96);
 
 #[cfg(test)]
 mod tests {
diff --git a/eth2/utils/bls/src/fake_signature.rs b/eth2/utils/bls/src/fake_signature.rs
index 3208ed992..8a333b9c0 100644
--- a/eth2/utils/bls/src/fake_signature.rs
+++ b/eth2/utils/bls/src/fake_signature.rs
@@ -1,4 +1,5 @@
 use super::{PublicKey, SecretKey, BLS_SIG_BYTE_SIZE};
+use cached_tree_hash::cached_tree_hash_ssz_encoding_as_vector;
 use hex::encode as hex_encode;
 use serde::de::{Deserialize, Deserializer};
 use serde::ser::{Serialize, Serializer};
@@ -75,6 +76,7 @@ impl Decodable for FakeSignature {
 }
 
 tree_hash_ssz_encoding_as_vector!(FakeSignature);
+cached_tree_hash_ssz_encoding_as_vector!(FakeSignature, 96);
 
 impl Serialize for FakeSignature {
     fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
diff --git a/eth2/utils/bls/src/public_key.rs b/eth2/utils/bls/src/public_key.rs
index dcbbc622a..e6e4d3508 100644
--- a/eth2/utils/bls/src/public_key.rs
+++ b/eth2/utils/bls/src/public_key.rs
@@ -1,5 +1,6 @@
 use super::{SecretKey, BLS_PUBLIC_KEY_BYTE_SIZE};
 use bls_aggregates::PublicKey as RawPublicKey;
+use cached_tree_hash::cached_tree_hash_ssz_encoding_as_vector;
 use serde::de::{Deserialize, Deserializer};
 use serde::ser::{Serialize, Serializer};
 use serde_hex::{encode as hex_encode, HexVisitor};
@@ -106,6 +107,7 @@ impl<'de> Deserialize<'de> for PublicKey {
 }
 
 tree_hash_ssz_encoding_as_vector!(PublicKey);
+cached_tree_hash_ssz_encoding_as_vector!(PublicKey, 48);
 
 impl PartialEq for PublicKey {
     fn eq(&self, other: &PublicKey) -> bool {
@@ -129,6 +131,7 @@ impl Hash for PublicKey {
 mod tests {
     use super::*;
     use ssz::ssz_encode;
+    use tree_hash::TreeHash;
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -140,4 +143,21 @@ mod tests {
 
         assert_eq!(original, decoded);
     }
+
+    #[test]
+    pub fn test_cached_tree_hash() {
+        let sk = SecretKey::random();
+        let original = PublicKey::from_secret_key(&sk);
+
+        let mut hasher = cached_tree_hash::CachedTreeHasher::new(&original).unwrap();
+
+        assert_eq!(hasher.tree_hash_root().unwrap(), original.tree_hash_root());
+
+        let sk = SecretKey::random();
+        let modified = PublicKey::from_secret_key(&sk);
+
+        hasher.update(&modified).unwrap();
+
+        assert_eq!(hasher.tree_hash_root().unwrap(), modified.tree_hash_root());
+    }
 }
diff --git a/eth2/utils/bls/src/signature.rs b/eth2/utils/bls/src/signature.rs
index 3fb68dc53..75f43aaf4 100644
--- a/eth2/utils/bls/src/signature.rs
+++ b/eth2/utils/bls/src/signature.rs
@@ -1,5 +1,6 @@
 use super::{PublicKey, SecretKey, BLS_SIG_BYTE_SIZE};
 use bls_aggregates::Signature as RawSignature;
+use cached_tree_hash::cached_tree_hash_ssz_encoding_as_vector;
 use hex::encode as hex_encode;
 use serde::de::{Deserialize, Deserializer};
 use serde::ser::{Serialize, Serializer};
@@ -116,6 +117,7 @@ impl Decodable for Signature {
 }
 
 tree_hash_ssz_encoding_as_vector!(Signature);
+cached_tree_hash_ssz_encoding_as_vector!(Signature, 96);
 
 impl Serialize for Signature {
     /// Serde serialization is compliant the Ethereum YAML test format.
@@ -145,6 +147,7 @@ mod tests {
     use super::super::Keypair;
     use super::*;
     use ssz::ssz_encode;
+    use tree_hash::TreeHash;
 
     #[test]
     pub fn test_ssz_round_trip() {
@@ -158,6 +161,22 @@ mod tests {
         assert_eq!(original, decoded);
     }
 
+    #[test]
+    pub fn test_cached_tree_hash() {
+        let keypair = Keypair::random();
+        let original = Signature::new(&[42, 42], 0, &keypair.sk);
+
+        let mut hasher = cached_tree_hash::CachedTreeHasher::new(&original).unwrap();
+
+        assert_eq!(hasher.tree_hash_root().unwrap(), original.tree_hash_root());
+
+        let modified = Signature::new(&[99, 99], 0, &keypair.sk);
+
+        hasher.update(&modified).unwrap();
+
+        assert_eq!(hasher.tree_hash_root().unwrap(), modified.tree_hash_root());
+    }
+
     #[test]
     pub fn test_empty_signature() {
         let sig = Signature::empty_signature();
diff --git a/eth2/utils/boolean-bitfield/Cargo.toml b/eth2/utils/boolean-bitfield/Cargo.toml
index 61bbc60a8..dfc97ce77 100644
--- a/eth2/utils/boolean-bitfield/Cargo.toml
+++ b/eth2/utils/boolean-bitfield/Cargo.toml
@@ -5,6 +5,7 @@ authors = ["Paul Hauner <paul@paulhauner.com>"]
 edition = "2018"
 
 [dependencies]
+cached_tree_hash = { path = "../cached_tree_hash" }
 serde_hex = { path = "../serde_hex" }
 ssz = { path = "../ssz" }
 bit-vec = "0.5.0"
diff --git a/eth2/utils/boolean-bitfield/src/lib.rs b/eth2/utils/boolean-bitfield/src/lib.rs
index 1d0f1c02e..cdc58173f 100644
--- a/eth2/utils/boolean-bitfield/src/lib.rs
+++ b/eth2/utils/boolean-bitfield/src/lib.rs
@@ -3,6 +3,7 @@ extern crate ssz;
 
 use bit_reverse::LookupReverse;
 use bit_vec::BitVec;
+use cached_tree_hash::cached_tree_hash_bytes_as_list;
 use serde::de::{Deserialize, Deserializer};
 use serde::ser::{Serialize, Serializer};
 use serde_hex::{encode, PrefixedHexVisitor};
@@ -270,11 +271,31 @@ impl tree_hash::TreeHash for BooleanBitfield {
     }
 }
 
+cached_tree_hash_bytes_as_list!(BooleanBitfield);
+
 #[cfg(test)]
 mod tests {
     use super::*;
     use serde_yaml;
     use ssz::{decode, ssz_encode, SszStream};
+    use tree_hash::TreeHash;
+
+    #[test]
+    pub fn test_cached_tree_hash() {
+        let original = BooleanBitfield::from_bytes(&vec![18; 12][..]);
+
+        let mut hasher = cached_tree_hash::CachedTreeHasher::new(&original).unwrap();
+
+        assert_eq!(hasher.tree_hash_root().unwrap(), original.tree_hash_root());
+        /*
+
+        let modified = BooleanBitfield::from_bytes(&vec![2; 1][..]);
+
+        hasher.update(&modified).unwrap();
+
+        assert_eq!(hasher.tree_hash_root().unwrap(), modified.tree_hash_root());
+        */
+    }
 
     #[test]
     fn test_new_bitfield() {
diff --git a/eth2/utils/cached_tree_hash/src/impls.rs b/eth2/utils/cached_tree_hash/src/impls.rs
index 687e74918..a859a8847 100644
--- a/eth2/utils/cached_tree_hash/src/impls.rs
+++ b/eth2/utils/cached_tree_hash/src/impls.rs
@@ -1,12 +1,46 @@
 use super::*;
 use crate::merkleize::merkleize;
+use ethereum_types::H256;
 
 pub mod vec;
 
-impl CachedTreeHash<u64> for u64 {
+macro_rules! impl_for_single_leaf_int {
+    ($type: ident) => {
+        impl CachedTreeHash<$type> for $type {
+            fn new_tree_hash_cache(&self, _depth: usize) -> Result<TreeHashCache, Error> {
+                Ok(TreeHashCache::from_bytes(
+                    merkleize(self.to_le_bytes().to_vec()),
+                    false,
+                    None,
+                )?)
+            }
+
+            fn tree_hash_cache_schema(&self, depth: usize) -> BTreeSchema {
+                BTreeSchema::from_lengths(depth, vec![1])
+            }
+
+            fn update_tree_hash_cache(&self, cache: &mut TreeHashCache) -> Result<(), Error> {
+                let leaf = merkleize(self.to_le_bytes().to_vec());
+                cache.maybe_update_chunk(cache.chunk_index, &leaf)?;
+
+                cache.chunk_index += 1;
+
+                Ok(())
+            }
+        }
+    };
+}
+
+impl_for_single_leaf_int!(u8);
+impl_for_single_leaf_int!(u16);
+impl_for_single_leaf_int!(u32);
+impl_for_single_leaf_int!(u64);
+impl_for_single_leaf_int!(usize);
+
+impl CachedTreeHash<bool> for bool {
     fn new_tree_hash_cache(&self, _depth: usize) -> Result<TreeHashCache, Error> {
         Ok(TreeHashCache::from_bytes(
-            merkleize(self.to_le_bytes().to_vec()),
+            merkleize((*self as u8).to_le_bytes().to_vec()),
             false,
             None,
         )?)
@@ -17,20 +51,19 @@ impl CachedTreeHash<u64> for u64 {
     }
 
     fn update_tree_hash_cache(&self, cache: &mut TreeHashCache) -> Result<(), Error> {
-        let leaf = merkleize(self.to_le_bytes().to_vec());
+        let leaf = merkleize((*self as u8).to_le_bytes().to_vec());
         cache.maybe_update_chunk(cache.chunk_index, &leaf)?;
 
         cache.chunk_index += 1;
-        // cache.overlay_index += 1;
 
         Ok(())
     }
 }
 
-impl CachedTreeHash<usize> for usize {
+impl CachedTreeHash<[u8; 4]> for [u8; 4] {
     fn new_tree_hash_cache(&self, _depth: usize) -> Result<TreeHashCache, Error> {
         Ok(TreeHashCache::from_bytes(
-            merkleize(self.to_le_bytes().to_vec()),
+            merkleize(self.to_vec()),
             false,
             None,
         )?)
@@ -41,11 +74,33 @@ impl CachedTreeHash<usize> for usize {
     }
 
     fn update_tree_hash_cache(&self, cache: &mut TreeHashCache) -> Result<(), Error> {
-        let leaf = merkleize(self.to_le_bytes().to_vec());
+        let leaf = merkleize(self.to_vec());
+        cache.maybe_update_chunk(cache.chunk_index, &leaf)?;
+
+        cache.chunk_index += 1;
+
+        Ok(())
+    }
+}
+
+impl CachedTreeHash<H256> for H256 {
+    fn new_tree_hash_cache(&self, _depth: usize) -> Result<TreeHashCache, Error> {
+        Ok(TreeHashCache::from_bytes(
+            merkleize(self.as_bytes().to_vec()),
+            false,
+            None,
+        )?)
+    }
+
+    fn tree_hash_cache_schema(&self, depth: usize) -> BTreeSchema {
+        BTreeSchema::from_lengths(depth, vec![1])
+    }
+
+    fn update_tree_hash_cache(&self, cache: &mut TreeHashCache) -> Result<(), Error> {
+        let leaf = merkleize(self.as_bytes().to_vec());
         cache.maybe_update_chunk(cache.chunk_index, &leaf)?;
 
         cache.chunk_index += 1;
-        // cache.overlay_index += 1;
 
         Ok(())
     }
diff --git a/eth2/utils/cached_tree_hash/src/impls/vec.rs b/eth2/utils/cached_tree_hash/src/impls/vec.rs
index f8ed32399..87ea3bcc3 100644
--- a/eth2/utils/cached_tree_hash/src/impls/vec.rs
+++ b/eth2/utils/cached_tree_hash/src/impls/vec.rs
@@ -95,6 +95,11 @@ pub fn update_tree_hash_cache<T: CachedTreeHash<T>>(
     let old_overlay = cache.get_overlay(cache.schema_index, cache.chunk_index)?;
     let new_overlay = BTreeOverlay::new(vec, cache.chunk_index, old_overlay.depth);
 
+    dbg!(cache.schema_index);
+    dbg!(cache.schemas.len());
+    dbg!(&old_overlay);
+    dbg!(&new_overlay);
+
     cache.replace_overlay(cache.schema_index, cache.chunk_index, new_overlay.clone())?;
 
     cache.schema_index += 1;
diff --git a/eth2/utils/cached_tree_hash/src/lib.rs b/eth2/utils/cached_tree_hash/src/lib.rs
index 316d52d07..24bbe0b07 100644
--- a/eth2/utils/cached_tree_hash/src/lib.rs
+++ b/eth2/utils/cached_tree_hash/src/lib.rs
@@ -1,4 +1,5 @@
 use hashing::hash;
+use merkleize::num_unsanitized_leaves;
 use std::ops::Range;
 use tree_hash::{TreeHash, TreeHashType, BYTES_PER_CHUNK, HASHSIZE};
 
@@ -62,3 +63,92 @@ impl CachedTreeHasher {
         Ok(self.cache.root()?.to_vec())
     }
 }
+
+#[macro_export]
+macro_rules! cached_tree_hash_ssz_encoding_as_vector {
+    ($type: ident, $num_bytes: expr) => {
+        impl cached_tree_hash::CachedTreeHash<$type> for $type {
+            fn new_tree_hash_cache(
+                &self,
+                depth: usize,
+            ) -> Result<cached_tree_hash::TreeHashCache, cached_tree_hash::Error> {
+                let (cache, _schema) = cached_tree_hash::impls::vec::new_tree_hash_cache(
+                    &ssz::ssz_encode(self),
+                    depth,
+                )?;
+
+                Ok(cache)
+            }
+
+            fn tree_hash_cache_schema(&self, depth: usize) -> cached_tree_hash::BTreeSchema {
+                let lengths =
+                    vec![1; cached_tree_hash::merkleize::num_unsanitized_leaves($num_bytes)];
+                cached_tree_hash::BTreeSchema::from_lengths(depth, lengths)
+            }
+
+            fn update_tree_hash_cache(
+                &self,
+                cache: &mut cached_tree_hash::TreeHashCache,
+            ) -> Result<(), cached_tree_hash::Error> {
+                cached_tree_hash::impls::vec::update_tree_hash_cache(
+                    &ssz::ssz_encode(self),
+                    cache,
+                )?;
+
+                Ok(())
+            }
+        }
+    };
+}
+
+#[macro_export]
+macro_rules! cached_tree_hash_bytes_as_list {
+    ($type: ident) => {
+        impl cached_tree_hash::CachedTreeHash<$type> for $type {
+            fn new_tree_hash_cache(
+                &self,
+                depth: usize,
+            ) -> Result<cached_tree_hash::TreeHashCache, cached_tree_hash::Error> {
+                let bytes = self.to_bytes();
+
+                let (mut cache, schema) =
+                    cached_tree_hash::impls::vec::new_tree_hash_cache(&bytes, depth)?;
+
+                cache.add_length_nodes(schema.into_overlay(0).chunk_range(), bytes.len())?;
+
+                Ok(cache)
+            }
+
+            fn num_tree_hash_cache_chunks(&self) -> usize {
+                // Add two extra nodes to cater for the node before and after to allow mixing-in length.
+                cached_tree_hash::BTreeOverlay::new(self, 0, 0).num_chunks() + 2
+            }
+
+            fn tree_hash_cache_schema(&self, depth: usize) -> cached_tree_hash::BTreeSchema {
+                cached_tree_hash::impls::vec::produce_schema(&ssz::ssz_encode(self), depth)
+            }
+
+            fn update_tree_hash_cache(
+                &self,
+                cache: &mut cached_tree_hash::TreeHashCache,
+            ) -> Result<(), cached_tree_hash::Error> {
+                let bytes = self.to_bytes();
+
+                // Skip the length-mixed-in root node.
+                cache.chunk_index += 1;
+
+                // Update the cache, returning the new overlay.
+                let new_overlay =
+                    cached_tree_hash::impls::vec::update_tree_hash_cache(&bytes, cache)?;
+
+                // Mix in length
+                cache.mix_in_length(new_overlay.chunk_range(), bytes.len())?;
+
+                // Skip an extra node to clear the length node.
+                cache.chunk_index = new_overlay.next_node() + 1;
+
+                Ok(())
+            }
+        }
+    };
+}
diff --git a/eth2/utils/cached_tree_hash/src/merkleize.rs b/eth2/utils/cached_tree_hash/src/merkleize.rs
index 6bfa73888..e744961b0 100644
--- a/eth2/utils/cached_tree_hash/src/merkleize.rs
+++ b/eth2/utils/cached_tree_hash/src/merkleize.rs
@@ -60,7 +60,7 @@ fn last_leaf_needs_padding(num_bytes: usize) -> bool {
 }
 
 /// Rounds up
-fn num_unsanitized_leaves(num_bytes: usize) -> usize {
+pub fn num_unsanitized_leaves(num_bytes: usize) -> usize {
     (num_bytes + HASHSIZE - 1) / HASHSIZE
 }
 
diff --git a/eth2/utils/cached_tree_hash/tests/tests.rs b/eth2/utils/cached_tree_hash/tests/tests.rs
index 8837fa1da..bc93e0176 100644
--- a/eth2/utils/cached_tree_hash/tests/tests.rs
+++ b/eth2/utils/cached_tree_hash/tests/tests.rs
@@ -231,6 +231,41 @@ pub struct StructWithVecOfStructs {
     pub c: Vec<Inner>,
 }
 
+fn get_inners() -> Vec<Inner> {
+    vec![
+        Inner {
+            a: 12,
+            b: 13,
+            c: 14,
+            d: 15,
+        },
+        Inner {
+            a: 99,
+            b: 100,
+            c: 101,
+            d: 102,
+        },
+        Inner {
+            a: 255,
+            b: 256,
+            c: 257,
+            d: 0,
+        },
+        Inner {
+            a: 1000,
+            b: 2000,
+            c: 3000,
+            d: 0,
+        },
+        Inner {
+            a: 0,
+            b: 0,
+            c: 0,
+            d: 0,
+        },
+    ]
+}
+
 fn get_struct_with_vec_of_structs() -> Vec<StructWithVecOfStructs> {
     let inner_a = Inner {
         a: 12,
@@ -342,6 +377,56 @@ fn test_struct_with_vec_of_struct_with_vec_of_structs() {
     }
 }
 
+#[derive(Clone, Debug, TreeHash, CachedTreeHash)]
+pub struct StructWithTwoVecs {
+    pub a: Vec<Inner>,
+    pub b: Vec<Inner>,
+}
+
+#[test]
+fn test_struct_with_two_vecs() {
+    let inners = get_inners();
+
+    let variants = vec![
+        StructWithTwoVecs {
+            a: inners[..].to_vec(),
+            b: inners[..].to_vec(),
+        },
+        StructWithTwoVecs {
+            a: inners[0..1].to_vec(),
+            b: inners[..].to_vec(),
+        },
+        StructWithTwoVecs {
+            a: inners[0..1].to_vec(),
+            b: inners[0..2].to_vec(),
+        },
+        StructWithTwoVecs {
+            a: inners[0..4].to_vec(),
+            b: inners[0..2].to_vec(),
+        },
+        StructWithTwoVecs {
+            a: vec![],
+            b: inners[..].to_vec(),
+        },
+        StructWithTwoVecs {
+            a: inners[..].to_vec(),
+            b: vec![],
+        },
+        StructWithTwoVecs {
+            a: inners[0..3].to_vec(),
+            b: inners[0..1].to_vec(),
+        },
+    ];
+
+    test_routine(variants[0].clone(), variants[6..7].to_vec());
+
+    /*
+    for v in &variants {
+        test_routine(v.clone(), variants.clone());
+    }
+    */
+}
+
 #[derive(Clone, Debug, TreeHash, CachedTreeHash)]
 pub struct Inner {
     pub a: u64,
diff --git a/eth2/utils/tree_hash/src/impls.rs b/eth2/utils/tree_hash/src/impls.rs
index f2ff8c2bc..e8485dc2f 100644
--- a/eth2/utils/tree_hash/src/impls.rs
+++ b/eth2/utils/tree_hash/src/impls.rs
@@ -52,7 +52,7 @@ impl TreeHash for bool {
 
 impl TreeHash for [u8; 4] {
     fn tree_hash_type() -> TreeHashType {
-        TreeHashType::List
+        TreeHashType::Vector
     }
 
     fn tree_hash_packed_encoding(&self) -> Vec<u8> {