diff --git a/src/proto/streams/mod.rs b/src/proto/streams/mod.rs
index 931adbc..27bf157 100644
--- a/src/proto/streams/mod.rs
+++ b/src/proto/streams/mod.rs
@@ -3,6 +3,10 @@ mod recv;
 mod send;
 mod state;
 mod store;
+mod stream;
+mod streams;
+
+pub use self::streams::Streams;
 
 use self::flow_control::FlowControl;
 use self::recv::Recv;
@@ -15,30 +19,6 @@ use proto::*;
 use error::Reason::*;
 use error::User::*;
 
-// TODO: All the VecDeques should become linked lists using the State
-// values.
-#[derive(Debug)]
-pub struct Streams<P> {
-    /// State related to managing the set of streams.
-    inner: Inner<P>,
-
-    /// Streams
-    streams: Store,
-}
-
-/// Fields needed to manage state related to managing the set of streams. This
-/// is mostly split out to make ownership happy.
-///
-/// TODO: better name
-#[derive(Debug)]
-struct Inner<P> {
-    /// Manages state transitions initiated by receiving frames
-    recv: Recv<P>,
-
-    /// Manages state transitions initiated by sending frames
-    send: Send<P>,
-}
-
 #[derive(Debug)]
 pub struct Config {
     /// Maximum number of remote initiated streams
@@ -53,218 +33,3 @@ pub struct Config {
     /// Initial window size of locally initiated streams
     pub init_local_window_sz: WindowSize,
 }
-
-impl<P: Peer> Streams<P> {
-    pub fn new(config: Config) -> Self {
-        Streams {
-            inner: Inner {
-                recv: Recv::new(&config),
-                send: Send::new(&config),
-            },
-            streams: Store::new(),
-        }
-    }
-
-    pub fn recv_headers(&mut self, frame: frame::Headers)
-        -> Result<Option<frame::Headers>, ConnectionError>
-    {
-        let id = frame.stream_id();
-
-        let state = match self.streams.entry(id) {
-            Entry::Occupied(e) => e.into_mut(),
-            Entry::Vacant(e) => {
-                // Trailers cannot open a stream. Trailers are header frames
-                // that do not contain pseudo headers. Requests MUST contain a
-                // method and responses MUST contain a status. If they do not,t
-                // hey are considered to be malformed.
-                if frame.is_trailers() {
-                    return Err(ProtocolError.into());
-                }
-
-                match try!(self.inner.recv.open(id)) {
-                    Some(state) => e.insert(state),
-                    None => return Ok(None),
-                }
-            }
-        };
-
-        if frame.is_trailers() {
-            if !frame.is_end_stream() {
-                // TODO: What error should this return?
-                unimplemented!();
-            }
-
-            try!(self.inner.recv.recv_eos(state));
-        } else {
-            try!(self.inner.recv.recv_headers(state, frame.is_end_stream()));
-        }
-
-        if state.is_closed() {
-            self.inner.dec_num_streams(id);
-        }
-
-        Ok(Some(frame))
-    }
-
-    pub fn recv_data(&mut self, frame: &frame::Data)
-        -> Result<(), ConnectionError>
-    {
-        let id = frame.stream_id();
-
-        let state = match self.streams.get_mut(&id) {
-            Some(state) => state,
-            None => return Err(ProtocolError.into()),
-        };
-
-        // Ensure there's enough capacity on the connection before acting on the
-        // stream.
-        try!(self.inner.recv.recv_data(frame, state));
-
-        if state.is_closed() {
-            self.inner.dec_num_streams(id);
-        }
-
-        Ok(())
-    }
-
-    pub fn recv_reset(&mut self, _frame: &frame::Reset)
-        -> Result<(), ConnectionError>
-    {
-        unimplemented!();
-    }
-
-    pub fn recv_window_update(&mut self, frame: frame::WindowUpdate)
-        -> Result<(), ConnectionError> {
-        let id = frame.stream_id();
-
-        if id.is_zero() {
-            try!(self.inner.send.recv_connection_window_update(frame));
-        } else {
-            // The remote may send window updates for streams that the local now
-            // considers closed. It's ok...
-            if let Some(state) = self.streams.get_mut(&id) {
-                try!(self.inner.send.recv_stream_window_update(frame, state));
-            }
-        }
-
-        Ok(())
-    }
-
-    pub fn recv_push_promise(&mut self, _frame: frame::PushPromise)
-        -> Result<(), ConnectionError>
-    {
-        unimplemented!();
-    }
-
-    pub fn send_headers(&mut self, frame: &frame::Headers)
-        -> Result<(), ConnectionError>
-    {
-        let id = frame.stream_id();
-
-        trace!("send_headers; id={:?}", id);
-
-        let state = match self.streams.entry(id) {
-            Entry::Occupied(e) => e.into_mut(),
-            Entry::Vacant(e) => {
-                // Trailers cannot open a stream. Trailers are header frames
-                // that do not contain pseudo headers. Requests MUST contain a
-                // method and responses MUST contain a status. If they do not,t
-                // hey are considered to be malformed.
-                if frame.is_trailers() {
-                    // TODO: Should this be a different error?
-                    return Err(UnexpectedFrameType.into());
-                }
-
-                let state = try!(self.inner.send.open(id));
-                e.insert(state)
-            }
-        };
-
-        if frame.is_trailers() {
-            try!(self.inner.send.send_eos(state));
-        } else {
-            try!(self.inner.send.send_headers(state, frame.is_end_stream()));
-        }
-
-        if state.is_closed() {
-            self.inner.dec_num_streams(id);
-        }
-
-        Ok(())
-    }
-
-    pub fn send_data<B: Buf>(&mut self, frame: &frame::Data<B>)
-        -> Result<(), ConnectionError>
-    {
-        let id = frame.stream_id();
-
-        let state = match self.streams.get_mut(&id) {
-            Some(state) => state,
-            None => return Err(UnexpectedFrameType.into()),
-        };
-
-        // Ensure there's enough capacity on the connection before acting on the
-        // stream.
-        try!(self.inner.send.send_data(frame, state));
-
-        if state.is_closed() {
-            self.inner.dec_num_streams(id);
-        }
-
-        Ok(())
-    }
-
-    pub fn poll_window_update(&mut self)
-        -> Poll<WindowUpdate, ConnectionError>
-    {
-        self.inner.send.poll_window_update(&mut self.streams)
-    }
-
-    pub fn expand_window(&mut self, id: StreamId, sz: WindowSize)
-        -> Result<(), ConnectionError>
-    {
-        if id.is_zero() {
-            try!(self.inner.recv.expand_connection_window(sz));
-        } else {
-            if let Some(state) = self.streams.get_mut(&id) {
-                try!(self.inner.recv.expand_stream_window(id, sz, state));
-            }
-        }
-
-        Ok(())
-    }
-
-    pub fn send_pending_refusal<T, B>(&mut self, dst: &mut Codec<T, B>)
-        -> Poll<(), ConnectionError>
-        where T: AsyncWrite,
-              B: Buf,
-    {
-        self.inner.recv.send_pending_refusal(dst)
-    }
-
-    pub fn send_pending_window_updates<T, B>(&mut self, dst: &mut Codec<T, B>)
-        -> Poll<(), ConnectionError>
-        where T: AsyncWrite,
-              B: Buf,
-    {
-        try_ready!(self.inner.recv.send_connection_window_update(dst));
-        try_ready!(self.inner.recv.send_stream_window_update(&mut self.streams, dst));
-
-        Ok(().into())
-    }
-}
-
-impl<P: Peer> Inner<P> {
-    fn dec_num_streams(&mut self, id: StreamId) {
-        if self.is_local_init(id) {
-            self.send.dec_num_streams();
-        } else {
-            self.recv.dec_num_streams();
-        }
-    }
-
-    fn is_local_init(&self, id: StreamId) -> bool {
-        assert!(!id.is_zero());
-        P::is_server() == id.is_server_initiated()
-    }
-}
diff --git a/src/proto/streams/stream.rs b/src/proto/streams/stream.rs
new file mode 100644
index 0000000..e69de29
diff --git a/src/proto/streams/streams.rs b/src/proto/streams/streams.rs
new file mode 100644
index 0000000..11da177
--- /dev/null
+++ b/src/proto/streams/streams.rs
@@ -0,0 +1,266 @@
+use proto::*;
+use super::*;
+
+use std::sync::{Arc, Mutex};
+
+// TODO: All the VecDeques should become linked lists using the State
+// values.
+#[derive(Debug)]
+pub struct Streams<P> {
+    inner: Arc<Mutex<Inner<P>>>,
+}
+
+/// Fields needed to manage state related to managing the set of streams. This
+/// is mostly split out to make ownership happy.
+///
+/// TODO: better name
+#[derive(Debug)]
+struct Inner<P> {
+    actions: Actions<P>,
+    store: Store,
+}
+
+#[derive(Debug)]
+struct Actions<P> {
+    /// Manages state transitions initiated by receiving frames
+    recv: Recv<P>,
+
+    /// Manages state transitions initiated by sending frames
+    send: Send<P>,
+}
+
+impl<P: Peer> Streams<P> {
+    pub fn new(config: Config) -> Self {
+        Streams {
+            inner: Arc::new(Mutex::new(Inner {
+                actions: Actions {
+                    recv: Recv::new(&config),
+                    send: Send::new(&config),
+                },
+                store: Store::new(),
+            })),
+        }
+    }
+
+    pub fn recv_headers(&mut self, frame: frame::Headers)
+        -> Result<Option<frame::Headers>, ConnectionError>
+    {
+        let id = frame.stream_id();
+        let mut me = self.inner.lock().unwrap();
+        let me = &mut *me;
+
+        let state = match me.store.entry(id) {
+            Entry::Occupied(e) => e.into_mut(),
+            Entry::Vacant(e) => {
+                // Trailers cannot open a stream. Trailers are header frames
+                // that do not contain pseudo headers. Requests MUST contain a
+                // method and responses MUST contain a status. If they do not,t
+                // hey are considered to be malformed.
+                if frame.is_trailers() {
+                    return Err(ProtocolError.into());
+                }
+
+                match try!(me.actions.recv.open(id)) {
+                    Some(state) => e.insert(state),
+                    None => return Ok(None),
+                }
+            }
+        };
+
+        if frame.is_trailers() {
+            if !frame.is_end_stream() {
+                // TODO: What error should this return?
+                unimplemented!();
+            }
+
+            try!(me.actions.recv.recv_eos(state));
+        } else {
+            try!(me.actions.recv.recv_headers(state, frame.is_end_stream()));
+        }
+
+        if state.is_closed() {
+            me.actions.dec_num_streams(id);
+        }
+
+        Ok(Some(frame))
+    }
+
+    pub fn recv_data(&mut self, frame: &frame::Data)
+        -> Result<(), ConnectionError>
+    {
+        let id = frame.stream_id();
+        let mut me = self.inner.lock().unwrap();
+        let me = &mut *me;
+
+        let state = match me.store.get_mut(&id) {
+            Some(state) => state,
+            None => return Err(ProtocolError.into()),
+        };
+
+        // Ensure there's enough capacity on the connection before acting on the
+        // stream.
+        try!(me.actions.recv.recv_data(frame, state));
+
+        if state.is_closed() {
+            me.actions.dec_num_streams(id);
+        }
+
+        Ok(())
+    }
+
+    pub fn recv_reset(&mut self, _frame: &frame::Reset)
+        -> Result<(), ConnectionError>
+    {
+        unimplemented!();
+    }
+
+    pub fn recv_window_update(&mut self, frame: frame::WindowUpdate)
+        -> Result<(), ConnectionError> {
+        let id = frame.stream_id();
+        let mut me = self.inner.lock().unwrap();
+        let me = &mut *me;
+
+        if id.is_zero() {
+            try!(me.actions.send.recv_connection_window_update(frame));
+        } else {
+            // The remote may send window updates for streams that the local now
+            // considers closed. It's ok...
+            if let Some(state) = me.store.get_mut(&id) {
+                try!(me.actions.send.recv_stream_window_update(frame, state));
+            }
+        }
+
+        Ok(())
+    }
+
+    pub fn recv_push_promise(&mut self, _frame: frame::PushPromise)
+        -> Result<(), ConnectionError>
+    {
+        unimplemented!();
+    }
+
+    pub fn send_headers(&mut self, frame: &frame::Headers)
+        -> Result<(), ConnectionError>
+    {
+        let id = frame.stream_id();
+        let mut me = self.inner.lock().unwrap();
+        let me = &mut *me;
+
+        trace!("send_headers; id={:?}", id);
+
+        let state = match me.store.entry(id) {
+            Entry::Occupied(e) => e.into_mut(),
+            Entry::Vacant(e) => {
+                // Trailers cannot open a stream. Trailers are header frames
+                // that do not contain pseudo headers. Requests MUST contain a
+                // method and responses MUST contain a status. If they do not,t
+                // hey are considered to be malformed.
+                if frame.is_trailers() {
+                    // TODO: Should this be a different error?
+                    return Err(UnexpectedFrameType.into());
+                }
+
+                let state = try!(me.actions.send.open(id));
+                e.insert(state)
+            }
+        };
+
+        if frame.is_trailers() {
+            try!(me.actions.send.send_eos(state));
+        } else {
+            try!(me.actions.send.send_headers(state, frame.is_end_stream()));
+        }
+
+        if state.is_closed() {
+            me.actions.dec_num_streams(id);
+        }
+
+        Ok(())
+    }
+
+    pub fn send_data<B: Buf>(&mut self, frame: &frame::Data<B>)
+        -> Result<(), ConnectionError>
+    {
+        let id = frame.stream_id();
+        let mut me = self.inner.lock().unwrap();
+        let me = &mut *me;
+
+        let state = match me.store.get_mut(&id) {
+            Some(state) => state,
+            None => return Err(UnexpectedFrameType.into()),
+        };
+
+        // Ensure there's enough capacity on the connection before acting on the
+        // stream.
+        try!(me.actions.send.send_data(frame, state));
+
+        if state.is_closed() {
+            me.actions.dec_num_streams(id);
+        }
+
+        Ok(())
+    }
+
+    pub fn poll_window_update(&mut self)
+        -> Poll<WindowUpdate, ConnectionError>
+    {
+        let mut me = self.inner.lock().unwrap();
+        let me = &mut *me;
+        me.actions.send.poll_window_update(&mut me.store)
+    }
+
+    pub fn expand_window(&mut self, id: StreamId, sz: WindowSize)
+        -> Result<(), ConnectionError>
+    {
+        let mut me = self.inner.lock().unwrap();
+        let me = &mut *me;
+
+        if id.is_zero() {
+            try!(me.actions.recv.expand_connection_window(sz));
+        } else {
+            if let Some(state) = me.store.get_mut(&id) {
+                try!(me.actions.recv.expand_stream_window(id, sz, state));
+            }
+        }
+
+        Ok(())
+    }
+
+    pub fn send_pending_refusal<T, B>(&mut self, dst: &mut Codec<T, B>)
+        -> Poll<(), ConnectionError>
+        where T: AsyncWrite,
+              B: Buf,
+    {
+        let mut me = self.inner.lock().unwrap();
+        let me = &mut *me;
+        me.actions.recv.send_pending_refusal(dst)
+    }
+
+    pub fn send_pending_window_updates<T, B>(&mut self, dst: &mut Codec<T, B>)
+        -> Poll<(), ConnectionError>
+        where T: AsyncWrite,
+              B: Buf,
+    {
+        let mut me = self.inner.lock().unwrap();
+        let me = &mut *me;
+        try_ready!(me.actions.recv.send_connection_window_update(dst));
+        try_ready!(me.actions.recv.send_stream_window_update(&mut me.store, dst));
+
+        Ok(().into())
+    }
+}
+
+impl<P: Peer> Actions<P> {
+    fn dec_num_streams(&mut self, id: StreamId) {
+        if self.is_local_init(id) {
+            self.send.dec_num_streams();
+        } else {
+            self.recv.dec_num_streams();
+        }
+    }
+
+    fn is_local_init(&self, id: StreamId) -> bool {
+        assert!(!id.is_zero());
+        P::is_server() == id.is_server_initiated()
+    }
+}