diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index fbcd70210..49128872c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -42,6 +42,11 @@ jobs:
             export PATH=$HOME/bin:$PATH
             cargo test
 
+      - name: cargo test (Celo)
+        run: |
+            export PATH=$HOME/bin:$PATH
+            cargo test --all-features
+
       - name: cargo fmt
         run: cargo fmt --all -- --check
 
diff --git a/Cargo.lock b/Cargo.lock
index f0ce7e714..292efc2e8 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -155,6 +155,15 @@ version = "0.1.10"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "4785bdd1c96b2a846b2bd7cc02e86b6b3dbf14e7e53446c4f54c92a361040822"
 
+[[package]]
+name = "cloudabi"
+version = "0.0.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ddfc5b9aa5d4507acaf872de71051dfd0e309860e88966e1051e462a077aac4f"
+dependencies = [
+ "bitflags",
+]
+
 [[package]]
 name = "crunchy"
 version = "0.2.2"
@@ -301,6 +310,7 @@ dependencies = [
  "rustc-hex",
  "serde",
  "serde_json",
+ "serial_test",
  "thiserror",
  "tokio",
 ]
@@ -775,6 +785,15 @@ dependencies = [
  "vcpkg",
 ]
 
+[[package]]
+name = "lock_api"
+version = "0.3.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c4da24a77a3d8a6d4862d95f72e6fdb9c09a643ecdb402d754004a557f2bec75"
+dependencies = [
+ "scopeguard",
+]
+
 [[package]]
 name = "log"
 version = "0.4.8"
@@ -897,6 +916,30 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "parking_lot"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d3a704eb390aafdc107b0e392f56a82b668e3a71366993b5340f5833fd62505e"
+dependencies = [
+ "lock_api",
+ "parking_lot_core",
+]
+
+[[package]]
+name = "parking_lot_core"
+version = "0.7.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d58c7c768d4ba344e3e8d72518ac13e259d7c7ade24167003b8488e10b6740a3"
+dependencies = [
+ "cfg-if",
+ "cloudabi",
+ "libc",
+ "redox_syscall",
+ "smallvec",
+ "winapi 0.3.8",
+]
+
 [[package]]
 name = "percent-encoding"
 version = "2.1.0"
@@ -1156,6 +1199,12 @@ dependencies = [
  "winapi 0.3.8",
 ]
 
+[[package]]
+name = "scopeguard"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
+
 [[package]]
 name = "sct"
 version = "0.6.0"
@@ -1209,6 +1258,28 @@ dependencies = [
  "url",
 ]
 
+[[package]]
+name = "serial_test"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fef5f7c7434b2f2c598adc6f9494648a1e41274a75c0ba4056f680ae0c117fd6"
+dependencies = [
+ "lazy_static",
+ "parking_lot",
+ "serial_test_derive",
+]
+
+[[package]]
+name = "serial_test_derive"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d08338d8024b227c62bd68a12c7c9883f5c66780abaef15c550dc56f46ee6515"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn",
+]
+
 [[package]]
 name = "sha2"
 version = "0.8.2"
diff --git a/README.md b/README.md
index facf414fc..c5e55c79c 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,6 @@
 # <h1 align="center"> ethers.rs </h1>
 
-**Complete Ethereum wallet implementation and utilities in Rust**
+**Complete Ethereum and Celo wallet implementation and utilities in Rust**
 
 [![CircleCI](https://circleci.com/gh/circleci/circleci-docs.svg?style=svg)](https://circleci.com/gh/circleci/circleci-docs)
 
@@ -20,6 +20,24 @@ ethers = { git = "github.com/gakonst/ethers-rs" }
 
 </details>
 
+### Celo Support
+
+[Celo](http://celo.org/) support is turned on via the feature-flag `celo`:
+
+```toml
+[dependencies]
+
+ethers = { git = "github.com/gakonst/ethers-rs", features = ["celo"] }
+```
+
+Celo's transactions differ from Ethereum transactions by including 3 new fields:
+- `fee_currency`: The currency fees are paid in (None for CELO, otherwise it's an Address)
+- `gateway_fee_recipient`: The address of the fee recipient (None for no gateway fee paid)
+- `gateway_fee`: Gateway fee amount (None for no gateway fee paid)
+
+The feature flag enables these additional fields in the transaction request builders and
+in the transactions which are fetched over JSON-RPC.
+
 ## Features
 
 - [x] Ethereum JSON-RPC Client
@@ -28,6 +46,7 @@ ethers = { git = "github.com/gakonst/ethers-rs" }
 - [x] Querying past events
 - [x] Event monitoring as `Stream`s
 - [x] ENS as a first class citizen
+- [x] Celo support
 - [ ] Websockets / `eth_subscribe`
 - [ ] Hardware Wallet Support
 - [ ] WASM Bindings
diff --git a/ethers-contract/Cargo.toml b/ethers-contract/Cargo.toml
index 97ec36758..0677f9bc9 100644
--- a/ethers-contract/Cargo.toml
+++ b/ethers-contract/Cargo.toml
@@ -22,7 +22,8 @@ futures = "0.3.5"
 ethers = { version = "0.1.0", path = "../ethers" }
 tokio = { version = "0.2.21", default-features = false, features = ["macros"] }
 serde_json = "1.0.55"
+serial_test = "0.4.0"
 
 [features]
 abigen = ["ethers-contract-abigen", "ethers-contract-derive"]
-celo = ["ethers-core/celo", "ethers-providers/celo", "ethers-signers/celo", "ethers/celo"]
+celo = ["ethers-core/celo", "ethers-core/celo", "ethers-providers/celo", "ethers-signers/celo"]
diff --git a/ethers-contract/src/factory.rs b/ethers-contract/src/factory.rs
index 9ac362692..0413dc412 100644
--- a/ethers-contract/src/factory.rs
+++ b/ethers-contract/src/factory.rs
@@ -10,9 +10,10 @@ use ethers_signers::{Client, Signer};
 #[derive(Debug, Clone)]
 /// Helper which manages the deployment transaction of a smart contract
 pub struct Deployer<'a, P, S> {
+    /// The deployer's transaction, exposed for overriding the defaults
+    pub tx: TransactionRequest,
     abi: Abi,
     client: &'a Client<P, S>,
-    tx: TransactionRequest,
     confs: usize,
 }
 
diff --git a/ethers-contract/tests/contract.rs b/ethers-contract/tests/contract.rs
index 8e97e5b5f..871740539 100644
--- a/ethers-contract/tests/contract.rs
+++ b/ethers-contract/tests/contract.rs
@@ -1,69 +1,190 @@
-use ethers_contract::ContractFactory;
-use ethers_core::{
-    types::{Address, H256},
-    utils::Ganache,
-};
+use ethers::{contract::ContractFactory, types::H256};
 
 mod common;
 pub use common::*;
 
-#[tokio::test]
-async fn deploy_and_call_contract() {
-    let (abi, bytecode) = compile();
-
-    // launch ganache
-    let _ganache = Ganache::new()
-        .mnemonic("abstract vacuum mammal awkward pudding scene penalty purchase dinner depart evoke puzzle")
-        .spawn();
-
-    // Instantiate the clients. We assume that clients consume the provider and the wallet
-    // (which makes sense), so for multi-client tests, you must clone the provider.
-    let client = connect("380eb0f3d505f087e438eca80bc4df9a7faa24f868e69fc0440261a0fc0567dc");
-    let client2 = connect("cc96601bc52293b53c4736a12af9130abf347669b3813f9ec4cafdf6991b087e");
-
-    // create a factory which will be used to deploy instances of the contract
-    let factory = ContractFactory::new(abi, bytecode, &client);
-
-    // `send` consumes the deployer so it must be cloned for later re-use
-    // (practically it's not expected that you'll need to deploy multiple instances of
-    // the _same_ deployer, so it's fine to clone here from a dev UX vs perf tradeoff)
-    let deployer = factory.deploy("initial value".to_string()).unwrap();
-    let contract = deployer.clone().send().await.unwrap();
-
-    let get_value = contract.method::<_, String>("getValue", ()).unwrap();
-    let last_sender = contract.method::<_, Address>("lastSender", ()).unwrap();
-
-    // the initial value must be the one set in the constructor
-    let value = get_value.clone().call().await.unwrap();
-    assert_eq!(value, "initial value");
-
-    // make a call with `client2`
-    let _tx_hash = contract
-        .connect(&client2)
-        .method::<_, H256>("setValue", "hi".to_owned())
-        .unwrap()
-        .send()
-        .await
-        .unwrap();
-    assert_eq!(last_sender.clone().call().await.unwrap(), client2.address());
-    assert_eq!(get_value.clone().call().await.unwrap(), "hi");
-
-    // we can also call contract methods at other addresses with the `at` call
-    // (useful when interacting with multiple ERC20s for example)
-    let contract2_addr = deployer.clone().send().await.unwrap().address();
-    let contract2 = contract.at(contract2_addr);
-    let init_value: String = contract2
-        .method::<_, String>("getValue", ())
-        .unwrap()
-        .call()
-        .await
-        .unwrap();
-    let init_address = contract2
-        .method::<_, Address>("lastSender", ())
-        .unwrap()
-        .call()
-        .await
-        .unwrap();
-    assert_eq!(init_address, Address::zero());
-    assert_eq!(init_value, "initial value");
+#[cfg(not(feature = "celo"))]
+mod eth_tests {
+    use super::*;
+    use ethers::{providers::StreamExt, types::Address, utils::Ganache};
+    use serial_test::serial;
+
+    #[tokio::test]
+    #[serial]
+    async fn deploy_and_call_contract() {
+        let (abi, bytecode) = compile();
+
+        // launch ganache
+        let _ganache = Ganache::new()
+            .mnemonic("abstract vacuum mammal awkward pudding scene penalty purchase dinner depart evoke puzzle")
+            .spawn();
+
+        // Instantiate the clients. We assume that clients consume the provider and the wallet
+        // (which makes sense), so for multi-client tests, you must clone the provider.
+        let client = connect("380eb0f3d505f087e438eca80bc4df9a7faa24f868e69fc0440261a0fc0567dc");
+        let client2 = connect("cc96601bc52293b53c4736a12af9130abf347669b3813f9ec4cafdf6991b087e");
+
+        // create a factory which will be used to deploy instances of the contract
+        let factory = ContractFactory::new(abi, bytecode, &client);
+
+        // `send` consumes the deployer so it must be cloned for later re-use
+        // (practically it's not expected that you'll need to deploy multiple instances of
+        // the _same_ deployer, so it's fine to clone here from a dev UX vs perf tradeoff)
+        let deployer = factory.deploy("initial value".to_string()).unwrap();
+        let contract = deployer.clone().send().await.unwrap();
+
+        let get_value = contract.method::<_, String>("getValue", ()).unwrap();
+        let last_sender = contract.method::<_, Address>("lastSender", ()).unwrap();
+
+        // the initial value must be the one set in the constructor
+        let value = get_value.clone().call().await.unwrap();
+        assert_eq!(value, "initial value");
+
+        // make a call with `client2`
+        let _tx_hash = contract
+            .connect(&client2)
+            .method::<_, H256>("setValue", "hi".to_owned())
+            .unwrap()
+            .send()
+            .await
+            .unwrap();
+        assert_eq!(last_sender.clone().call().await.unwrap(), client2.address());
+        assert_eq!(get_value.clone().call().await.unwrap(), "hi");
+
+        // we can also call contract methods at other addresses with the `at` call
+        // (useful when interacting with multiple ERC20s for example)
+        let contract2_addr = deployer.clone().send().await.unwrap().address();
+        let contract2 = contract.at(contract2_addr);
+        let init_value: String = contract2
+            .method::<_, String>("getValue", ())
+            .unwrap()
+            .call()
+            .await
+            .unwrap();
+        let init_address = contract2
+            .method::<_, Address>("lastSender", ())
+            .unwrap()
+            .call()
+            .await
+            .unwrap();
+        assert_eq!(init_address, Address::zero());
+        assert_eq!(init_value, "initial value");
+    }
+
+    #[tokio::test]
+    #[serial]
+    async fn get_past_events() {
+        let (abi, bytecode) = compile();
+        let client = connect("380eb0f3d505f087e438eca80bc4df9a7faa24f868e69fc0440261a0fc0567dc");
+        let (_ganache, contract) = deploy(&client, abi, bytecode).await;
+
+        // make a call with `client2`
+        let _tx_hash = contract
+            .method::<_, H256>("setValue", "hi".to_owned())
+            .unwrap()
+            .send()
+            .await
+            .unwrap();
+
+        // and we can fetch the events
+        let logs: Vec<ValueChanged> = contract
+            .event("ValueChanged")
+            .unwrap()
+            .from_block(0u64)
+            .topic1(client.address()) // Corresponds to the first indexed parameter
+            .query()
+            .await
+            .unwrap();
+        assert_eq!(logs[0].new_value, "initial value");
+        assert_eq!(logs[1].new_value, "hi");
+        assert_eq!(logs.len(), 2);
+    }
+
+    #[tokio::test]
+    #[serial]
+    async fn watch_events() {
+        let (abi, bytecode) = compile();
+        let client = connect("380eb0f3d505f087e438eca80bc4df9a7faa24f868e69fc0440261a0fc0567dc");
+        let (_ganache, contract) = deploy(&client, abi, bytecode).await;
+
+        // We spawn the event listener:
+        let mut stream = contract
+            .event::<ValueChanged>("ValueChanged")
+            .unwrap()
+            .stream()
+            .await
+            .unwrap();
+
+        let num_calls = 3u64;
+
+        // and we make a few calls
+        for i in 0..num_calls {
+            let _tx_hash = contract
+                .method::<_, H256>("setValue", i.to_string())
+                .unwrap()
+                .send()
+                .await
+                .unwrap();
+        }
+
+        for i in 0..num_calls {
+            // unwrap the option of the stream, then unwrap the decoding result
+            let log = stream.next().await.unwrap().unwrap();
+            assert_eq!(log.new_value, i.to_string());
+        }
+    }
+}
+
+#[cfg(feature = "celo")]
+mod celo_tests {
+    use super::*;
+    use ethers::{
+        providers::{Http, Provider},
+        signers::Wallet,
+    };
+    use std::convert::TryFrom;
+
+    #[tokio::test]
+    async fn deploy_and_call_contract() {
+        let (abi, bytecode) = compile();
+
+        // Celo testnet
+        let provider =
+            Provider::<Http>::try_from("https://alfajores-forno.celo-testnet.org").unwrap();
+
+        // Funded with https://celo.org/developers/faucet
+        let client = "d652abb81e8c686edba621a895531b1f291289b63b5ef09a94f686a5ecdd5db1"
+            .parse::<Wallet>()
+            .unwrap()
+            .connect(provider);
+
+        let factory = ContractFactory::new(abi, bytecode, &client);
+        let deployer = factory.deploy("initial value".to_string()).unwrap();
+        let contract = deployer.send().await.unwrap();
+
+        let value: String = contract
+            .method("getValue", ())
+            .unwrap()
+            .call()
+            .await
+            .unwrap();
+        assert_eq!(value, "initial value");
+
+        // make a state mutating transaction
+        let pending_tx = contract
+            .method::<_, H256>("setValue", "hi".to_owned())
+            .unwrap()
+            .send()
+            .await
+            .unwrap();
+        let _receipt = pending_tx.await.unwrap();
+
+        let value: String = contract
+            .method("getValue", ())
+            .unwrap()
+            .call()
+            .await
+            .unwrap();
+        assert_eq!(value, "hi");
+    }
 }
diff --git a/ethers-contract/tests/get_past_events.rs b/ethers-contract/tests/get_past_events.rs
deleted file mode 100644
index dcd51ed14..000000000
--- a/ethers-contract/tests/get_past_events.rs
+++ /dev/null
@@ -1,32 +0,0 @@
-use ethers_core::types::H256;
-
-mod common;
-use common::{compile, connect, deploy, ValueChanged};
-
-#[tokio::test]
-async fn get_past_events() {
-    let (abi, bytecode) = compile();
-    let client = connect("380eb0f3d505f087e438eca80bc4df9a7faa24f868e69fc0440261a0fc0567dc");
-    let (_ganache, contract) = deploy(&client, abi, bytecode).await;
-
-    // make a call with `client2`
-    let _tx_hash = contract
-        .method::<_, H256>("setValue", "hi".to_owned())
-        .unwrap()
-        .send()
-        .await
-        .unwrap();
-
-    // and we can fetch the events
-    let logs: Vec<ValueChanged> = contract
-        .event("ValueChanged")
-        .unwrap()
-        .from_block(0u64)
-        .topic1(client.address()) // Corresponds to the first indexed parameter
-        .query()
-        .await
-        .unwrap();
-    assert_eq!(logs[0].new_value, "initial value");
-    assert_eq!(logs[1].new_value, "hi");
-    assert_eq!(logs.len(), 2);
-}
diff --git a/ethers-contract/tests/watch_events.rs b/ethers-contract/tests/watch_events.rs
deleted file mode 100644
index d8b9ccaa3..000000000
--- a/ethers-contract/tests/watch_events.rs
+++ /dev/null
@@ -1,38 +0,0 @@
-use ethers_core::types::H256;
-use ethers_providers::StreamExt;
-
-mod common;
-use common::{compile, connect, deploy, ValueChanged};
-
-#[tokio::test]
-async fn watch_events() {
-    let (abi, bytecode) = compile();
-    let client = connect("380eb0f3d505f087e438eca80bc4df9a7faa24f868e69fc0440261a0fc0567dc");
-    let (_ganache, contract) = deploy(&client, abi, bytecode).await;
-
-    // We spawn the event listener:
-    let mut stream = contract
-        .event::<ValueChanged>("ValueChanged")
-        .unwrap()
-        .stream()
-        .await
-        .unwrap();
-
-    let num_calls = 3u64;
-
-    // and we make a few calls
-    for i in 0..num_calls {
-        let _tx_hash = contract
-            .method::<_, H256>("setValue", i.to_string())
-            .unwrap()
-            .send()
-            .await
-            .unwrap();
-    }
-
-    for i in 0..num_calls {
-        // unwrap the option of the stream, then unwrap the decoding result
-        let log = stream.next().await.unwrap().unwrap();
-        assert_eq!(log.new_value, i.to_string());
-    }
-}
diff --git a/ethers/Cargo.toml b/ethers/Cargo.toml
index 2e5a72f99..50d887312 100644
--- a/ethers/Cargo.toml
+++ b/ethers/Cargo.toml
@@ -32,7 +32,7 @@ celo = [
     "ethers-core/celo",
     "ethers-providers/celo",
     "ethers-signers/celo",
-    "ethers-contract/celo"
+    "ethers-contract/celo",
 ]
 
 core = ["ethers-core"]