diff --git a/src/executive.rs b/src/executive.rs
index ea95c69e4..8252b9221 100644
--- a/src/executive.rs
+++ b/src/executive.rs
@@ -2,7 +2,9 @@
 use common::*;
 use state::*;
 use engine::*;
-use evm::{self, Schedule, Factory, Ext};
+use evm::{self, Factory, Ext};
+use externalities::*;
+use substate::*;
 
 /// Returns new address created from address and given nonce.
 pub fn contract_address(address: &Address, nonce: &U256) -> Address {
@@ -12,38 +14,6 @@ pub fn contract_address(address: &Address, nonce: &U256) -> Address {
 	From::from(stream.out().sha3())
 }
 
-/// State changes which should be applied in finalize,
-/// after transaction is fully executed.
-pub struct Substate {
-	/// Any accounts that have suicided.
-	suicides: HashSet<Address>,
-	/// Any logs.
-	logs: Vec<LogEntry>,
-	/// Refund counter of SSTORE nonzero->zero.
-	refunds_count: U256,
-	/// Created contracts.
-	contracts_created: Vec<Address>
-}
-
-impl Substate {
-	/// Creates new substate.
-	pub fn new() -> Self {
-		Substate {
-			suicides: HashSet::new(),
-			logs: vec![],
-			refunds_count: U256::zero(),
-			contracts_created: vec![]
-		}
-	}
-
-	pub fn accrue(&mut self, s: Substate) {
-		self.suicides.extend(s.suicides.into_iter());
-		self.logs.extend(s.logs.into_iter());
-		self.refunds_count = self.refunds_count + s.refunds_count;
-		self.contracts_created.extend(s.contracts_created.into_iter());
-	}
-}
-
 /// Transaction execution receipt.
 #[derive(Debug)]
 pub struct Executed {
@@ -89,7 +59,7 @@ impl<'a> Executive<'a> {
 	}
 
 	/// Populates executive from parent properties. Increments executive depth.
-	fn from_parent(state: &'a mut State, info: &'a EnvInfo, engine: &'a Engine, depth: usize) -> Self {
+	pub fn from_parent(state: &'a mut State, info: &'a EnvInfo, engine: &'a Engine, depth: usize) -> Self {
 		Executive::new_with_depth(state, info, engine, depth + 1)
 	}
 
@@ -104,8 +74,13 @@ impl<'a> Executive<'a> {
 		}
 	}
 
+	/// Creates `Externalities` from `Executive`.
+	pub fn to_externalities<'_>(&'_ mut self, params: &'_ ActionParams, substate: &'_ mut Substate, output: OutputPolicy<'_>) -> Externalities {
+		Externalities::new(self.state, self.info, self.engine, self.depth, params, substate, output)
+	}
+
 	/// This funtion should be used to execute transaction.
-	pub fn transact(&mut self, t: &Transaction) -> Result<Executed, Error> {
+	pub fn transact(&'a mut self, t: &Transaction) -> Result<Executed, Error> {
 		let sender = try!(t.sender());
 		let nonce = self.state.nonce(&sender);
 
@@ -198,13 +173,15 @@ impl<'a> Executive<'a> {
 		self.state.transfer_balance(&params.sender, &params.address, &params.value);
 
 		if self.engine.is_builtin(&params.code_address) {
+			// if destination is builtin, try to execute it
+			
 			let default = [];
 			let data = if let &Some(ref d) = &params.data { d as &[u8] } else { &default as &[u8] };
-			// if destination is builtin, try to execute it
-			let cost = self.engine.cost_of_builtin(&params.code_address, &data);
+
+			let cost = self.engine.cost_of_builtin(&params.code_address, data);
 			match cost <= params.gas {
 				true => {
-					self.engine.execute_builtin(&params.code_address, &data, &mut output);
+					self.engine.execute_builtin(&params.code_address, data, &mut output);
 					Ok(params.gas - cost)
 				},
 				// just drain the whole gas
@@ -220,7 +197,7 @@ impl<'a> Executive<'a> {
 			let mut unconfirmed_substate = Substate::new();
 
 			let res = {
-				let mut ext = Externalities::from_executive(self, params, &mut unconfirmed_substate, OutputPolicy::Return(output));
+				let mut ext = self.to_externalities(params, &mut unconfirmed_substate, OutputPolicy::Return(output));
 				let evm = Factory::create();
 				evm.exec(&params, &mut ext)
 			};
@@ -235,7 +212,7 @@ impl<'a> Executive<'a> {
 	/// Creates contract with given contract params.
 	/// NOTE. It does not finalize the transaction (doesn't do refunds, nor suicides).
 	/// Modifies the substate.
-	fn create(&mut self, params: &ActionParams, substate: &mut Substate) -> evm::Result {
+	pub fn create(&mut self, params: &ActionParams, substate: &mut Substate) -> evm::Result {
 		// backup used in case of running out of gas
 		let backup = self.state.clone();
 
@@ -249,7 +226,7 @@ impl<'a> Executive<'a> {
 		self.state.transfer_balance(&params.sender, &params.address, &params.value);
 
 		let res = {
-			let mut ext = Externalities::from_executive(self, params, &mut unconfirmed_substate, OutputPolicy::InitContract);
+			let mut ext = self.to_externalities(params, &mut unconfirmed_substate, OutputPolicy::InitContract);
 			let evm = Factory::create();
 			evm.exec(&params, &mut ext)
 		};
@@ -324,231 +301,6 @@ impl<'a> Executive<'a> {
 	}
 }
 
-/// Policy for handling output data on `RETURN` opcode.
-pub enum OutputPolicy<'a> {
-	/// Return reference to fixed sized output.
-	/// Used for message calls.
-	Return(BytesRef<'a>),
-	/// Init new contract as soon as `RETURN` is called.
-	InitContract
-}
-
-/// Implementation of evm Externalities.
-pub struct Externalities<'a> {
-	#[cfg(test)]
-	pub state: &'a mut State,
-	#[cfg(not(test))]
-	state: &'a mut State,
-	info: &'a EnvInfo,
-	engine: &'a Engine,
-	depth: usize,
-	#[cfg(test)]
-	pub params: &'a ActionParams,
-	#[cfg(not(test))]
-	params: &'a ActionParams,
-	substate: &'a mut Substate,
-	schedule: Schedule,
-	output: OutputPolicy<'a>
-}
-
-impl<'a> Externalities<'a> {
-	/// Basic `Externalities` constructor.
-	pub fn new(state: &'a mut State, 
-			   info: &'a EnvInfo, 
-			   engine: &'a Engine, 
-			   depth: usize,
-			   params: &'a ActionParams, 
-			   substate: &'a mut Substate, 
-			   output: OutputPolicy<'a>) -> Self {
-		Externalities {
-			state: state,
-			info: info,
-			engine: engine,
-			depth: depth,
-			params: params,
-			substate: substate,
-			schedule: engine.schedule(info),
-			output: output
-		}
-	}
-
-	/// Creates `Externalities` from `Executive`.
-	fn from_executive(e: &'a mut Executive, params: &'a ActionParams, substate: &'a mut Substate, output: OutputPolicy<'a>) -> Self {
-		Self::new(e.state, e.info, e.engine, e.depth, params, substate, output)
-	}
-}
-
-impl<'a> Ext for Externalities<'a> {
-	fn sload(&self, key: &H256) -> H256 {
-		self.state.storage_at(&self.params.address, key)
-	}
-
-	fn sstore(&mut self, key: H256, value: H256) {
-		// if SSTORE nonzero -> zero, increment refund count
-		if value == H256::new() && self.state.storage_at(&self.params.address, &key) != H256::new() {
-			self.substate.refunds_count = self.substate.refunds_count + U256::one();
-		}
-		self.state.set_storage(&self.params.address, key, value)
-	}
-
-	fn balance(&self, address: &Address) -> U256 {
-		self.state.balance(address)
-	}
-
-	fn blockhash(&self, number: &U256) -> H256 {
-		match *number < U256::from(self.info.number) && number.low_u64() >= cmp::max(256, self.info.number) - 256 {
-			true => {
-				let index = self.info.number - number.low_u64() - 1;
-				self.info.last_hashes[index as usize].clone()
-			},
-			false => H256::from(&U256::zero()),
-		}
-	}
-
-	fn create(&mut self, gas: &U256, value: &U256, code: &[u8]) -> (U256, Option<Address>) {
-		// if balance is insufficient or we are to deep, return
-		if self.state.balance(&self.params.address) < *value || self.depth >= self.schedule.max_depth {
-			return (*gas, None);
-		}
-
-		// create new contract address
-		let address = contract_address(&self.params.address, &self.state.nonce(&self.params.address));
-
-		// prepare the params
-		let params = ActionParams {
-			code_address: address.clone(),
-			address: address.clone(),
-			sender: self.params.address.clone(),
-			origin: self.params.origin.clone(),
-			gas: *gas,
-			gas_price: self.params.gas_price.clone(),
-			value: value.clone(),
-			code: Some(code.to_vec()),
-			data: None
-		};
-
-		let mut ex = Executive::from_parent(self.state, self.info, self.engine, self.depth);
-		ex.state.inc_nonce(&self.params.address);
-		match ex.create(&params, self.substate) {
-			Ok(gas_left) => (gas_left, Some(address)),
-			_ => (U256::zero(), None)
-		}
-	}
-
-	fn call(&mut self, 
-			gas: &U256, 
-			call_gas: &U256, 
-			receive_address: &Address, 
-			value: &U256, 
-			data: &[u8], 
-			code_address: &Address, 
-			output: &mut [u8]) -> Result<(U256, bool), evm::Error> {
-		let mut gas_cost = *call_gas;
-		let mut call_gas = *call_gas;
-
-		// TODO: move gas calculation out!
-		let is_call = receive_address == code_address;
-		if is_call && !self.state.exists(&code_address) {
-			gas_cost = gas_cost + U256::from(self.schedule.call_new_account_gas);
-		}
-
-		if *value > U256::zero() {
-			assert!(self.schedule.call_value_transfer_gas > self.schedule.call_stipend, "overflow possible");
-			gas_cost = gas_cost + U256::from(self.schedule.call_value_transfer_gas);
-			call_gas = call_gas + U256::from(self.schedule.call_stipend);
-		}
-
-		if gas_cost > *gas {
-			return Err(evm::Error::OutOfGas);
-		}
-
-		let gas = *gas - gas_cost;
-
-		// if balance is insufficient or we are too deep, return
-		if self.state.balance(&self.params.address) < *value || self.depth >= self.schedule.max_depth {
-			return Ok((gas + call_gas, true));
-		}
-
-		let params = ActionParams {
-			code_address: code_address.clone(),
-			address: receive_address.clone(), 
-			sender: self.params.address.clone(),
-			origin: self.params.origin.clone(),
-			gas: call_gas,
-			gas_price: self.params.gas_price.clone(),
-			value: value.clone(),
-			code: self.state.code(code_address),
-			data: Some(data.to_vec()),
-		};
-
-		let mut ex = Executive::from_parent(self.state, self.info, self.engine, self.depth);
-		match ex.call(&params, self.substate, BytesRef::Fixed(output)) {
-			Ok(gas_left) => Ok((gas + gas_left, true)),
-			_ => Ok((gas, false))
-		}
-	}
-
-	fn extcode(&self, address: &Address) -> Vec<u8> {
-		self.state.code(address).unwrap_or(vec![])
-	}
-
-	fn ret(&mut self, gas: &U256, data: &[u8]) -> Result<U256, evm::Error> {
-		match &mut self.output {
-			&mut OutputPolicy::Return(BytesRef::Fixed(ref mut slice)) => unsafe {
-				let len = cmp::min(slice.len(), data.len());
-				ptr::copy(data.as_ptr(), slice.as_mut_ptr(), len);
-				Ok(*gas)
-			},
-			&mut OutputPolicy::Return(BytesRef::Flexible(ref mut vec)) => unsafe {
-				vec.clear();
-				vec.reserve(data.len());
-				ptr::copy(data.as_ptr(), vec.as_mut_ptr(), data.len());
-				vec.set_len(data.len());
-				Ok(*gas)
-			},
-			&mut OutputPolicy::InitContract => {
-				let return_cost = U256::from(data.len()) * U256::from(self.schedule.create_data_gas);
-				if return_cost > *gas {
-					return match self.schedule.exceptional_failed_code_deposit {
-						true => Err(evm::Error::OutOfGas),
-						false => Ok(*gas)
-					}
-				}
-				let mut code = vec![];
-				code.reserve(data.len());
-				unsafe {
-					ptr::copy(data.as_ptr(), code.as_mut_ptr(), data.len());
-					code.set_len(data.len());
-				}
-				let address = &self.params.address;
-				self.state.init_code(address, code);
-				self.substate.contracts_created.push(address.clone());
-				Ok(*gas - return_cost)
-			}
-		}
-	}
-
-	fn log(&mut self, topics: Vec<H256>, data: Bytes) {
-		let address = self.params.address.clone();
-		self.substate.logs.push(LogEntry::new(address, topics, data));
-	}
-
-	fn suicide(&mut self, refund_address: &Address) {
-		let address = self.params.address.clone();
-		let balance = self.balance(&address);
-		self.state.transfer_balance(&address, refund_address, &balance);
-		self.substate.suicides.insert(address);
-	}
-
-	fn schedule(&self) -> &Schedule {
-		&self.schedule
-	}
-
-	fn env_info(&self) -> &EnvInfo {
-		&self.info
-	}
-}
-
 #[cfg(test)]
 mod tests {
 	use super::*;
@@ -558,6 +310,7 @@ mod tests {
 	use engine::*;
 	use spec::*;
 	use evm::Schedule;
+	use substate::*;
 
 	struct TestEngine {
 		spec: Spec,
diff --git a/src/externalities.rs b/src/externalities.rs
new file mode 100644
index 000000000..f5a72288a
--- /dev/null
+++ b/src/externalities.rs
@@ -0,0 +1,230 @@
+//! Transaction Execution environment.
+use common::*;
+use state::*;
+use engine::*;
+use executive::*;
+use evm::{self, Schedule, Ext};
+use substate::*;
+
+/// Policy for handling output data on `RETURN` opcode.
+pub enum OutputPolicy<'a> {
+	/// Return reference to fixed sized output.
+	/// Used for message calls.
+	Return(BytesRef<'a>),
+	/// Init new contract as soon as `RETURN` is called.
+	InitContract
+}
+
+/// Implementation of evm Externalities.
+pub struct Externalities<'a> {
+	
+	#[cfg(test)]
+	pub state: &'a mut State,
+	#[cfg(not(test))]
+	state: &'a mut State,
+
+	info: &'a EnvInfo,
+	engine: &'a Engine,
+	depth: usize,
+	
+	#[cfg(test)]
+	pub params: &'a ActionParams,
+	#[cfg(not(test))]
+	params: &'a ActionParams,
+	
+	substate: &'a mut Substate,
+	schedule: Schedule,
+	output: OutputPolicy<'a>
+}
+
+impl<'a> Externalities<'a> {
+	/// Basic `Externalities` constructor.
+	pub fn new(state: &'a mut State, 
+			   info: &'a EnvInfo, 
+			   engine: &'a Engine, 
+			   depth: usize,
+			   params: &'a ActionParams, 
+			   substate: &'a mut Substate, 
+			   output: OutputPolicy<'a>) -> Self {
+		Externalities {
+			state: state,
+			info: info,
+			engine: engine,
+			depth: depth,
+			params: params,
+			substate: substate,
+			schedule: engine.schedule(info),
+			output: output
+		}
+	}
+}
+
+impl<'a> Ext for Externalities<'a> {
+	fn sload(&self, key: &H256) -> H256 {
+		self.state.storage_at(&self.params.address, key)
+	}
+
+	fn sstore(&mut self, key: H256, value: H256) {
+		// if SSTORE nonzero -> zero, increment refund count
+		if value == H256::new() && self.state.storage_at(&self.params.address, &key) != H256::new() {
+			self.substate.refunds_count = self.substate.refunds_count + U256::one();
+		}
+		self.state.set_storage(&self.params.address, key, value)
+	}
+
+	fn balance(&self, address: &Address) -> U256 {
+		self.state.balance(address)
+	}
+
+	fn blockhash(&self, number: &U256) -> H256 {
+		match *number < U256::from(self.info.number) && number.low_u64() >= cmp::max(256, self.info.number) - 256 {
+			true => {
+				let index = self.info.number - number.low_u64() - 1;
+				self.info.last_hashes[index as usize].clone()
+			},
+			false => H256::from(&U256::zero()),
+		}
+	}
+
+	fn create(&mut self, gas: &U256, value: &U256, code: &[u8]) -> (U256, Option<Address>) {
+		// if balance is insufficient or we are to deep, return
+		if self.state.balance(&self.params.address) < *value || self.depth >= self.schedule.max_depth {
+			return (*gas, None);
+		}
+
+		// create new contract address
+		let address = contract_address(&self.params.address, &self.state.nonce(&self.params.address));
+
+		// prepare the params
+		let params = ActionParams {
+			code_address: address.clone(),
+			address: address.clone(),
+			sender: self.params.address.clone(),
+			origin: self.params.origin.clone(),
+			gas: *gas,
+			gas_price: self.params.gas_price.clone(),
+			value: value.clone(),
+			code: Some(code.to_vec()),
+			data: None,
+		};
+
+		self.state.inc_nonce(&self.params.address);
+		let mut ex = Executive::from_parent(self.state, self.info, self.engine, self.depth);
+		match ex.create(&params, self.substate) {
+			Ok(gas_left) => (gas_left, Some(address)),
+			_ => (U256::zero(), None)
+		}
+	}
+
+	fn call(&mut self, 
+			gas: &U256, 
+			call_gas: &U256, 
+			receive_address: &Address, 
+			value: &U256, 
+			data: &[u8], 
+			code_address: &Address, 
+			output: &mut [u8]) -> Result<(U256, bool), evm::Error> {
+		let mut gas_cost = *call_gas;
+		let mut call_gas = *call_gas;
+
+		let is_call = receive_address == code_address;
+		if is_call && !self.state.exists(&code_address) {
+			gas_cost = gas_cost + U256::from(self.schedule.call_new_account_gas);
+		}
+
+		if *value > U256::zero() {
+			assert!(self.schedule.call_value_transfer_gas > self.schedule.call_stipend, "overflow possible");
+			gas_cost = gas_cost + U256::from(self.schedule.call_value_transfer_gas);
+			call_gas = call_gas + U256::from(self.schedule.call_stipend);
+		}
+
+		if gas_cost > *gas {
+			return Err(evm::Error::OutOfGas);
+		}
+
+		let gas = *gas - gas_cost;
+
+		// if balance is insufficient or we are too deep, return
+		if self.state.balance(&self.params.address) < *value || self.depth >= self.schedule.max_depth {
+			return Ok((gas + call_gas, true));
+		}
+
+		let params = ActionParams {
+			code_address: code_address.clone(),
+			address: receive_address.clone(), 
+			sender: self.params.address.clone(),
+			origin: self.params.origin.clone(),
+			gas: call_gas,
+			gas_price: self.params.gas_price.clone(),
+			value: value.clone(),
+			code: self.state.code(code_address),
+			data: Some(data.to_vec()),
+		};
+
+		let mut ex = Executive::from_parent(self.state, self.info, self.engine, self.depth);
+		match ex.call(&params, self.substate, BytesRef::Fixed(output)) {
+			Ok(gas_left) => Ok((gas + gas_left, true)),
+			_ => Ok((gas, false))
+		}
+	}
+
+	fn extcode(&self, address: &Address) -> Vec<u8> {
+		self.state.code(address).unwrap_or(vec![])
+	}
+
+	fn ret(&mut self, gas: &U256, data: &[u8]) -> Result<U256, evm::Error> {
+		match &mut self.output {
+			&mut OutputPolicy::Return(BytesRef::Fixed(ref mut slice)) => unsafe {
+				let len = cmp::min(slice.len(), data.len());
+				ptr::copy(data.as_ptr(), slice.as_mut_ptr(), len);
+				Ok(*gas)
+			},
+			&mut OutputPolicy::Return(BytesRef::Flexible(ref mut vec)) => unsafe {
+				vec.clear();
+				vec.reserve(data.len());
+				ptr::copy(data.as_ptr(), vec.as_mut_ptr(), data.len());
+				vec.set_len(data.len());
+				Ok(*gas)
+			},
+			&mut OutputPolicy::InitContract => {
+				let return_cost = U256::from(data.len()) * U256::from(self.schedule.create_data_gas);
+				if return_cost > *gas {
+					return match self.schedule.exceptional_failed_code_deposit {
+						true => Err(evm::Error::OutOfGas),
+						false => Ok(*gas)
+					}
+				}
+				let mut code = vec![];
+				code.reserve(data.len());
+				unsafe {
+					ptr::copy(data.as_ptr(), code.as_mut_ptr(), data.len());
+					code.set_len(data.len());
+				}
+				let address = &self.params.address;
+				self.state.init_code(address, code);
+				self.substate.contracts_created.push(address.clone());
+				Ok(*gas - return_cost)
+			}
+		}
+	}
+
+	fn log(&mut self, topics: Vec<H256>, data: Bytes) {
+		let address = self.params.address.clone();
+		self.substate.logs.push(LogEntry::new(address, topics, data));
+	}
+
+	fn suicide(&mut self, refund_address: &Address) {
+		let address = self.params.address.clone();
+		let balance = self.balance(&address);
+		self.state.transfer_balance(&address, refund_address, &balance);
+		self.substate.suicides.insert(address);
+	}
+
+	fn schedule(&self) -> &Schedule {
+		&self.schedule
+	}
+
+	fn env_info(&self) -> &EnvInfo {
+		&self.info
+	}
+}
diff --git a/src/lib.rs b/src/lib.rs
index 0b81f4fd3..666edebae 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -89,7 +89,6 @@ extern crate ethcore_util as util;
 
 pub mod common;
 pub mod basic_types;
-pub mod executive;
 pub mod error;
 pub mod log_entry;
 pub mod env_info;
@@ -110,7 +109,10 @@ pub mod spec;
 pub mod views;
 pub mod blockchain;
 pub mod extras;
+pub mod substate;
 pub mod evm;
+pub mod executive;
+pub mod externalities;
 
 #[cfg(test)]
 mod tests;
diff --git a/src/substate.rs b/src/substate.rs
new file mode 100644
index 000000000..f85427745
--- /dev/null
+++ b/src/substate.rs
@@ -0,0 +1,33 @@
+use common::*;
+
+/// State changes which should be applied in finalize,
+/// after transaction is fully executed.
+pub struct Substate {
+	/// Any accounts that have suicided.
+	pub suicides: HashSet<Address>,
+	/// Any logs.
+	pub logs: Vec<LogEntry>,
+	/// Refund counter of SSTORE nonzero->zero.
+	pub refunds_count: U256,
+	/// Created contracts.
+	pub contracts_created: Vec<Address>
+}
+
+impl Substate {
+	/// Creates new substate.
+	pub fn new() -> Self {
+		Substate {
+			suicides: HashSet::new(),
+			logs: vec![],
+			refunds_count: U256::zero(),
+			contracts_created: vec![]
+		}
+	}
+
+	pub fn accrue(&mut self, s: Substate) {
+		self.suicides.extend(s.suicides.into_iter());
+		self.logs.extend(s.logs.into_iter());
+		self.refunds_count = self.refunds_count + s.refunds_count;
+		self.contracts_created.extend(s.contracts_created.into_iter());
+	}
+}
diff --git a/src/tests/executive.rs b/src/tests/executive.rs
index 6b59774a5..3e0eae4b5 100644
--- a/src/tests/executive.rs
+++ b/src/tests/executive.rs
@@ -6,6 +6,8 @@ use engine::*;
 use evm;
 use evm::{Schedule, Ext, Factory};
 use ethereum;
+use externalities::*;
+use substate::*;
 
 struct TestEngine {
 	spec: Spec,