diff --git a/src/state/active_state.rs b/src/state/active_state.rs
index 1cba78114..4aba069fc 100644
--- a/src/state/active_state.rs
+++ b/src/state/active_state.rs
@@ -1,6 +1,8 @@
 use super::partial_crosslink_record::PartialCrosslinkRecord;
 use super::recent_proposer_record::RecentPropserRecord;
 use super::rlp::{ RlpStream, Encodable };
+use super::rlp::encode as rlp_encode;
+use super::blake2::{ Blake2s, Digest };
 use super::utils::types::*;
 
 pub struct ActiveState {
@@ -33,6 +35,14 @@ impl ActiveState {
     pub fn num_recent_attesters(&self) -> usize {
         self.recent_attesters.len()
     }
+
+    pub fn blake2s_hash(&self) -> Blake2sDigest {
+        let mut hasher = Blake2s::new();
+        hasher.input(&rlp_encode(self).into_vec());
+        let mut digest = Blake2sDigest::new();
+        digest.clone_from_slice(hasher.result().as_slice());
+        digest
+    }
 }
 
 /*
diff --git a/src/state/block.rs b/src/state/block.rs
index 542056acb..17fd6bbea 100644
--- a/src/state/block.rs
+++ b/src/state/block.rs
@@ -49,7 +49,9 @@ impl Block {
         // s.append(&self.attestation_aggregate_sig);   // TODO: RLP this
         s.append_list(&self.shard_aggregate_votes);
         s.append(&self.main_chain_ref);
-        s.append_list(&self.state_hash);
+        // TODO: state hash serialization is probably incorrect.
+        s.append(&self.state_hash.crystallized_state);
+        s.append(&self.state_hash.active_state);
         let rlp_vec = s.out();
 
         // Parse the RLP vector into an array compatible with the BLS signer
@@ -89,7 +91,9 @@ impl Encodable for Block {
         // s.append(&self.attestation_aggregate_sig);   // TODO: RLP this
         s.append_list(&self.shard_aggregate_votes);
         s.append(&self.main_chain_ref);
-        s.append_list(&self.state_hash);
+        // TODO: state hash serialization is probably incorrect.
+        s.append(&self.state_hash.crystallized_state);
+        s.append(&self.state_hash.active_state);
         // s.append(&self.sig);    // TODO: RLP this
     }
 }
@@ -108,7 +112,7 @@ mod tests {
         let parent_hash = Sha256Digest::from([0; 32]);
         let randao_reveal = Sha256Digest::from([1; 32]);
         let main_chain_ref = Sha256Digest::from([2; 32]);
-        let state_hash = [0; 64];
+        let state_hash = StateHash::zero();
         let mut b = Block::new(parent_hash,
                            randao_reveal,
                            main_chain_ref,
@@ -128,7 +132,7 @@ mod tests {
         let mut b = Block::new(Sha256Digest::random(),
                            Sha256Digest::random(),
                            Sha256Digest::random(),
-                           [0; 64]);
+                           StateHash::zero());
 
         // Both signatures fail before signing
         assert_eq!(b.sig_verify(&alice_keypair.public), false);
@@ -152,11 +156,10 @@ mod tests {
             attestation_aggregate_sig: AggregateSignature::new(),
             shard_aggregate_votes: Vec::new(),
             main_chain_ref: Sha256Digest::zero(),
-            state_hash: [0; 64],
+            state_hash: StateHash::zero(),
             sig: None
         };
         let e = rlp::encode(&b);
-        println!("{:?}", e);
         assert_eq!(e.len(), 168);
         assert_eq!(e[0], 160);
         assert_eq!(e[1..33], [0; 32]);
diff --git a/src/state/crystallized_state.rs b/src/state/crystallized_state.rs
index d0dcc9eb6..9f232fd8d 100644
--- a/src/state/crystallized_state.rs
+++ b/src/state/crystallized_state.rs
@@ -1,8 +1,10 @@
-use super::utils::types::Sha256Digest;
+use super::utils::types::{ Sha256Digest, Blake2sDigest };
 use super::validator_record::ValidatorRecord;
 use super::crosslink_record::CrosslinkRecord;
 use super::rlp::{ RlpStream, Encodable };
+use super::rlp::encode as rlp_encode;
 use super::ethereum_types::U256;
+use super::blake2::{ Blake2s, Digest };
 
 pub struct CrystallizedState {
     pub active_validators: Vec<ValidatorRecord>,
@@ -36,6 +38,14 @@ impl CrystallizedState {
         self.crosslink_records.len()
 
     }
+    
+    pub fn blake2s_hash(&self) -> Blake2sDigest {
+        let mut hasher = Blake2s::new();
+        hasher.input(&rlp_encode(self).into_vec());
+        let mut digest = Blake2sDigest::new();
+        digest.clone_from_slice(hasher.result().as_slice());
+        digest
+    }
 }
 
 /*
diff --git a/src/state/mod.rs b/src/state/mod.rs
index 697730afc..b4162b7f2 100644
--- a/src/state/mod.rs
+++ b/src/state/mod.rs
@@ -1,5 +1,6 @@
 extern crate rlp;
 extern crate ethereum_types;
+extern crate blake2;
 
 use super::utils;
 
diff --git a/src/utils/mod.rs b/src/utils/mod.rs
index 51c03db67..59a7d823e 100644
--- a/src/utils/mod.rs
+++ b/src/utils/mod.rs
@@ -2,5 +2,8 @@ extern crate ethereum_types;
 extern crate blake2;
 extern crate crypto_mac;
 
+use super::state::active_state;
+use super::state::crystallized_state;
+
 pub mod types;
 pub mod bls;
diff --git a/src/utils/types.rs b/src/utils/types.rs
index 7940fe1de..f7fed2a90 100644
--- a/src/utils/types.rs
+++ b/src/utils/types.rs
@@ -1,4 +1,6 @@
 use super::ethereum_types::{ H256, H160 };
+use super::active_state::ActiveState;
+use super::crystallized_state::CrystallizedState;
 
 pub use super::blake2::Blake2s;
 
@@ -10,6 +12,25 @@ pub type Blake2sDigest = H256;
 
 pub type Address = H160;
 
-pub type StateHash = [u8; 64];
+pub struct StateHash {
+    pub active_state: Blake2sDigest,
+    pub crystallized_state: Blake2sDigest
+}
+
+impl StateHash {
+    pub fn zero() -> Self {
+        Self {
+            active_state: Blake2sDigest::zero(),
+            crystallized_state: Blake2sDigest::zero()
+        }
+    }
+
+    pub fn from_states(active: &ActiveState, crystal: &CrystallizedState) -> Self {
+        Self {
+            active_state: active.blake2s_hash(),
+            crystallized_state: crystal.blake2s_hash()
+        }
+    }
+}
 
 pub type Bitfield = Vec<u8>;