diff --git a/src/client.rs b/src/client.rs
index 439be61..c522451 100644
--- a/src/client.rs
+++ b/src/client.rs
@@ -60,7 +60,7 @@ impl Peer for Client {
         id.is_server_initiated()
     }
 
-    fn can_create_local_stream() -> bool {
+    fn local_can_open() -> bool {
         true
     }
 
diff --git a/src/lib.rs b/src/lib.rs
index 557f1d9..67b7c83 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -85,9 +85,9 @@ pub trait Peer {
     /// remote node.
     fn is_valid_remote_stream_id(id: StreamId) -> bool;
 
-    fn can_create_local_stream() -> bool;
-    fn can_create_remote_stream() -> bool {
-        !Self::can_create_local_stream()
+    fn local_can_open() -> bool;
+    fn remote_can_open() -> bool {
+        !Self::local_can_open()
     }
 
     //fn can_reserve_local_stream() -> bool;
diff --git a/src/proto/flow_control.rs b/src/proto/flow_control.rs
index 763bd00..d71a072 100644
--- a/src/proto/flow_control.rs
+++ b/src/proto/flow_control.rs
@@ -332,24 +332,32 @@ impl<T> ApplySettings for FlowControl<T>
 }
 
 impl<T: ControlStreams> ControlStreams for FlowControl<T> {
-    fn is_valid_local_id(id: StreamId) -> bool {
-        T::is_valid_local_id(id)
+    fn local_valid_id(id: StreamId) -> bool {
+        T::local_valid_id(id)
     }
 
-    fn is_valid_remote_id(id: StreamId) -> bool {
-        T::is_valid_remote_id(id)
+    fn remote_valid_id(id: StreamId) -> bool {
+        T::remote_valid_id(id)
     }
 
-    fn can_create_local_stream() -> bool {
-        T::can_create_local_stream()
+    fn local_can_open() -> bool {
+        T::local_can_open()
     }
 
-    fn close_stream_local_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
-        self.inner.close_stream_local_half(id)
+    fn local_open(&mut self, id: StreamId, sz: WindowSize) -> Result<(), ConnectionError> {
+        self.inner.local_open(id, sz)
     }
 
-    fn close_stream_remote_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
-        self.inner.close_stream_remote_half(id)
+    fn remote_open(&mut self, id: StreamId, sz: WindowSize) -> Result<(), ConnectionError> {
+        self.inner.remote_open(id, sz)
+    }
+
+    fn close_local_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
+        self.inner.close_local_half(id)
+    }
+
+    fn close_remote_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
+        self.inner.close_remote_half(id)
     }
 
     fn reset_stream(&mut self, id: StreamId, cause: Reason) {
diff --git a/src/proto/mod.rs b/src/proto/mod.rs
index 17b390a..9ed9fc0 100644
--- a/src/proto/mod.rs
+++ b/src/proto/mod.rs
@@ -31,7 +31,7 @@ use self::framed_write::FramedWrite;
 use self::ping_pong::{ControlPing, PingPayload, PingPong};
 use self::ready::ReadySink;
 use self::settings::{ApplySettings, /*ControlSettings,*/ Settings};
-use self::state::{StreamState};
+use self::state::{StreamState, PeerState};
 use self::stream_recv_close::StreamRecvClose;
 use self::stream_recv_open::StreamRecvOpen;
 use self::stream_send_close::StreamSendClose;
diff --git a/src/proto/settings.rs b/src/proto/settings.rs
index 730134a..887fce7 100644
--- a/src/proto/settings.rs
+++ b/src/proto/settings.rs
@@ -37,7 +37,7 @@ pub struct Settings<T> {
     remaining_acks: usize,
 
     // True when the local settings must be flushed to the remote
-    is_valid_local_id_dirty: bool,
+    local_valid_id_dirty: bool,
 
     // True when we have received a settings frame from the remote.
     received_remote: bool,
@@ -52,7 +52,7 @@ impl<T, U> Settings<T>
             local: local,
             remote: SettingSet::default(),
             remaining_acks: 0,
-            is_valid_local_id_dirty: true,
+            local_valid_id_dirty: true,
             received_remote: false,
         }
     }
@@ -74,18 +74,18 @@ impl<T, U> Settings<T>
             local: self.local,
             remote: self.remote,
             remaining_acks: self.remaining_acks,
-            is_valid_local_id_dirty: self.is_valid_local_id_dirty,
+            local_valid_id_dirty: self.local_valid_id_dirty,
             received_remote: self.received_remote,
         }
     }
 
     fn try_send_pending(&mut self) -> Poll<(), ConnectionError> {
-        trace!("try_send_pending; dirty={} acks={}", self.is_valid_local_id_dirty, self.remaining_acks);
-        if self.is_valid_local_id_dirty {
+        trace!("try_send_pending; dirty={} acks={}", self.local_valid_id_dirty, self.remaining_acks);
+        if self.local_valid_id_dirty {
             let frame = frame::Settings::new(self.local.clone());
             try_ready!(self.try_send(frame));
 
-            self.is_valid_local_id_dirty = false;
+            self.local_valid_id_dirty = false;
         }
 
         while self.remaining_acks > 0 {
@@ -111,7 +111,7 @@ impl<T, U> Settings<T>
 impl<T> ControlSettings for Settings<T>{
     fn update_local_settings(&mut self, local: frame::SettingSet) -> Result<(), ConnectionError> {
         self.local = local;
-        self.is_valid_local_id_dirty = true;
+        self.local_valid_id_dirty = true;
         Ok(())
     }
 
diff --git a/src/proto/stream_recv_close.rs b/src/proto/stream_recv_close.rs
index 6127a1d..90ce8a5 100644
--- a/src/proto/stream_recv_close.rs
+++ b/src/proto/stream_recv_close.rs
@@ -67,24 +67,32 @@ impl<T, U> ReadySink for StreamRecvClose<T>
 }
 
 impl<T: ControlStreams> ControlStreams for StreamRecvClose<T> {
-    fn is_valid_local_id(id: StreamId) -> bool {
-        T::is_valid_local_id(id)
+    fn local_valid_id(id: StreamId) -> bool {
+        T::local_valid_id(id)
     }
 
-    fn is_valid_remote_id(id: StreamId) -> bool {
-        T::is_valid_remote_id(id)
+    fn remote_valid_id(id: StreamId) -> bool {
+        T::remote_valid_id(id)
     }
 
-    fn can_create_local_stream() -> bool {
-        T::can_create_local_stream()
+    fn local_can_open() -> bool {
+        T::local_can_open()
     }
 
-    fn close_stream_local_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
-        self.inner.close_stream_local_half(id)
+    fn local_open(&mut self, id: StreamId, sz: WindowSize) -> Result<(), ConnectionError> {
+        self.inner.local_open(id, sz)
     }
 
-    fn close_stream_remote_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
-        self.inner.close_stream_remote_half(id)
+    fn remote_open(&mut self, id: StreamId, sz: WindowSize) -> Result<(), ConnectionError> {
+        self.inner.remote_open(id, sz)
+    }
+
+    fn close_local_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
+        self.inner.close_local_half(id)
+    }
+
+    fn close_remote_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
+        self.inner.close_remote_half(id)
     }
 
     fn reset_stream(&mut self, id: StreamId, cause: Reason) {
diff --git a/src/proto/stream_recv_open.rs b/src/proto/stream_recv_open.rs
index 2effe8c..ae32e64 100644
--- a/src/proto/stream_recv_open.rs
+++ b/src/proto/stream_recv_open.rs
@@ -121,23 +121,34 @@ impl<T, U> Stream for StreamRecvOpen<T>
                 continue;
             }
 
-            if T::is_valid_remote_id(id) {
-                if !self.inner.is_local_active(id) {
-                    if !T::can_create_remote_stream() {
+            if T::remote_valid_id(id) {
+                if !self.inner.is_remote_active(id) {
+                    if !T::remote_can_open() {
                         return Err(ProtocolError.into());
                     }
 
                     if let Some(max) = self.max_concurrency {
-                        if (max as usize) < self.inner.local_active_len() {
+                        if (max as usize) < self.inner.remote_active_len() {
                             return Err(RefusedStream.into());
                         }
                     }
-                }
 
-                // If the frame ends the stream, it will be handled in
-                // StreamRecvClose.
-                return Ok(Async::Ready(Some(frame)));
+                    self.inner.remote_open(id, self.initial_window_size)?;
+                }
+            } else {
+                // Receiving on local stream MUST be on active stream.
+                if !self.inner.is_local_active(id) && !frame.is_reset() {
+                    return Err(ProtocolError.into());
+                }
             }
+
+            if let &Data(..) = &frame {
+                self.inner.check_can_recv_data(id)?;
+            }
+
+            // If the frame ends the stream, it will be handled in
+            // StreamRecvClose.
+            return Ok(Async::Ready(Some(frame)));
         }
     }
 }
@@ -301,24 +312,32 @@ impl<T, U> ReadySink for StreamRecvOpen<T>
     // }
 
 impl<T: ControlStreams> ControlStreams for StreamRecvOpen<T> {
-    fn is_valid_local_id(id: StreamId) -> bool {
-        T::is_valid_local_id(id)
+    fn local_valid_id(id: StreamId) -> bool {
+        T::local_valid_id(id)
     }
 
-    fn is_valid_remote_id(id: StreamId) -> bool {
-        T::is_valid_remote_id(id)
+    fn remote_valid_id(id: StreamId) -> bool {
+        T::remote_valid_id(id)
     }
 
-    fn can_create_local_stream() -> bool {
-        T::can_create_local_stream()
+    fn local_can_open() -> bool {
+        T::local_can_open()
     }
 
-    fn close_stream_local_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
-        self.inner.close_stream_local_half(id)
+    fn local_open(&mut self, id: StreamId, sz: WindowSize) -> Result<(), ConnectionError> {
+        self.inner.local_open(id, sz)
     }
 
-    fn close_stream_remote_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
-        self.inner.close_stream_remote_half(id)
+    fn remote_open(&mut self, id: StreamId, sz: WindowSize) -> Result<(), ConnectionError> {
+        self.inner.remote_open(id, sz)
+    }
+
+    fn close_local_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
+        self.inner.close_local_half(id)
+    }
+
+    fn close_remote_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
+        self.inner.close_remote_half(id)
     }
 
     fn reset_stream(&mut self, id: StreamId, cause: Reason) {
diff --git a/src/proto/stream_send_close.rs b/src/proto/stream_send_close.rs
index 6c514d7..bb0c406 100644
--- a/src/proto/stream_send_close.rs
+++ b/src/proto/stream_send_close.rs
@@ -48,7 +48,7 @@ impl<T, U> Sink for StreamSendClose<T>
             if let &Frame::Reset(ref rst) = &frame {
                 self.inner.reset_stream(id, rst.reason());
             } else {
-                self.inner.close_stream_local_half(id)?;
+                self.inner.close_local_half(id)?;
             }
         }
 
@@ -81,24 +81,32 @@ impl<T: ApplySettings> ApplySettings for StreamSendClose<T> {
 }
 
 impl<T: ControlStreams> ControlStreams for StreamSendClose<T> {
-    fn is_valid_local_id(id: StreamId) -> bool {
-        T::is_valid_local_id(id)
+    fn local_valid_id(id: StreamId) -> bool {
+        T::local_valid_id(id)
     }
 
-    fn is_valid_remote_id(id: StreamId) -> bool {
-        T::is_valid_remote_id(id)
+    fn remote_valid_id(id: StreamId) -> bool {
+        T::remote_valid_id(id)
     }
 
-    fn can_create_local_stream() -> bool {
-        T::can_create_local_stream()
+    fn local_can_open() -> bool {
+        T::local_can_open()
     }
 
-    fn close_stream_local_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
-        self.inner.close_stream_local_half(id)
+    fn local_open(&mut self, id: StreamId, sz: WindowSize) -> Result<(), ConnectionError> {
+        self.inner.local_open(id, sz)
     }
 
-    fn close_stream_remote_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
-        self.inner.close_stream_remote_half(id)
+    fn remote_open(&mut self, id: StreamId, sz: WindowSize) -> Result<(), ConnectionError> {
+        self.inner.remote_open(id, sz)
+    }
+
+    fn close_local_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
+        self.inner.close_local_half(id)
+    }
+
+    fn close_remote_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
+        self.inner.close_remote_half(id)
     }
 
     fn reset_stream(&mut self, id: StreamId, cause: Reason) {
diff --git a/src/proto/stream_send_open.rs b/src/proto/stream_send_open.rs
index 19e746c..75eabe5 100644
--- a/src/proto/stream_send_open.rs
+++ b/src/proto/stream_send_open.rs
@@ -99,16 +99,19 @@ impl<T, U> Sink for StreamSendOpen<T>
             return Err(StreamReset(reason).into())
         }
 
-        if T::is_valid_local_id(id) {
-            if self.inner.is_local_active(id) {
-            } else if T::can_create_local_stream() {
+        if T::local_valid_id(id) {
+            if !self.inner.is_local_active(id) {
+                if !T::local_can_open() {
+                    return Err(InvalidStreamId.into());
+                }
+
                 if let Some(max) = self.max_concurrency {
                     if (max as usize) < self.inner.local_active_len() {
                         return Err(Rejected.into());
                     }
                 }
 
-                // TODO create that shit.
+                self.inner.local_open(id, self.initial_window_size)?;
             }
         } else {
             // If the frame was part of a remote stream, it MUST already exist.
@@ -118,7 +121,7 @@ impl<T, U> Sink for StreamSendOpen<T>
         }
 
         if let &Data(..) = &frame {
-            self.inner.check_can_send_data(id);
+            self.inner.check_can_send_data(id)?;
         }
 
         return self.inner.start_send(frame);
@@ -141,24 +144,32 @@ impl<T, U> ReadySink for StreamSendOpen<T>
 }
 
 impl<T: ControlStreams> ControlStreams for StreamSendOpen<T> {
-    fn is_valid_local_id(id: StreamId) -> bool {
-        T::is_valid_local_id(id)
+    fn local_valid_id(id: StreamId) -> bool {
+        T::local_valid_id(id)
     }
 
-    fn is_valid_remote_id(id: StreamId) -> bool {
-        T::is_valid_remote_id(id)
+    fn remote_valid_id(id: StreamId) -> bool {
+        T::remote_valid_id(id)
     }
 
-    fn can_create_local_stream() -> bool {
-        T::can_create_local_stream()
+    fn local_can_open() -> bool {
+        T::local_can_open()
     }
 
-    fn close_stream_local_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
-        self.inner.close_stream_local_half(id)
+    fn local_open(&mut self, id: StreamId, sz: WindowSize) -> Result<(), ConnectionError> {
+        self.inner.local_open(id, sz)
     }
 
-    fn close_stream_remote_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
-        self.inner.close_stream_remote_half(id)
+    fn remote_open(&mut self, id: StreamId, sz: WindowSize) -> Result<(), ConnectionError> {
+        self.inner.remote_open(id, sz)
+    }
+
+    fn close_local_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
+        self.inner.close_local_half(id)
+    }
+
+    fn close_remote_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
+        self.inner.close_remote_half(id)
     }
 
     fn reset_stream(&mut self, id: StreamId, cause: Reason) {
diff --git a/src/proto/stream_store.rs b/src/proto/stream_store.rs
index f46db7c..9508051 100644
--- a/src/proto/stream_store.rs
+++ b/src/proto/stream_store.rs
@@ -1,6 +1,7 @@
 use {ConnectionError, Peer, StreamId};
 use error::Reason::{NoError, ProtocolError};
 use proto::*;
+use proto::state::{StreamState, PeerState};
 
 use fnv::FnvHasher;
 use ordermap::OrderMap;
@@ -10,16 +11,23 @@ use std::marker::PhantomData;
 /// Exposes stream states to "upper" layers of the transport (i.e. from StreamTracker up
 /// to Connection).
 pub trait ControlStreams {
-    fn is_valid_local_id(id: StreamId) -> bool;
-    fn is_valid_remote_id(id: StreamId) -> bool;
+    fn local_valid_id(id: StreamId) -> bool;
+    fn remote_valid_id(id: StreamId) -> bool;
 
-    fn can_create_local_stream() -> bool;
-    fn can_create_remote_stream() -> bool {
-        !Self::can_create_local_stream()
+    fn local_can_open() -> bool;
+    fn remote_can_open() -> bool {
+        !Self::local_can_open()
     }
 
-    fn close_stream_local_half(&mut self, id: StreamId) -> Result<(), ConnectionError>;
-    fn close_stream_remote_half(&mut self, id: StreamId) -> Result<(), ConnectionError>;
+    fn local_open(&mut self, id: StreamId, sz: WindowSize) -> Result<(), ConnectionError>;
+    fn remote_open(&mut self, id: StreamId, sz: WindowSize) -> Result<(), ConnectionError>;
+
+    // fn local_reserve(&mut self, id: StreamId) -> Result<(), ConnectionError>;
+    // fn remote_reserve(&mut self, id: StreamId) -> Result<(), ConnectionError>;
+
+    fn close_local_half(&mut self, id: StreamId) -> Result<(), ConnectionError>;
+    fn close_remote_half(&mut self, id: StreamId) -> Result<(), ConnectionError>;
+
     fn reset_stream(&mut self, id: StreamId, cause: Reason);
     fn get_reset(&self, id: StreamId) -> Option<Reason>;
 
@@ -139,19 +147,46 @@ impl<T, P: Peer> StreamStore<T, P> {
 }
 
 impl<T, P: Peer> ControlStreams for StreamStore<T, P> {
-    fn is_valid_local_id(id: StreamId) -> bool {
+    fn local_valid_id(id: StreamId) -> bool {
         P::is_valid_local_stream_id(id)
     }
 
-    fn is_valid_remote_id(id: StreamId) -> bool {
+    fn remote_valid_id(id: StreamId) -> bool {
         P::is_valid_remote_stream_id(id)
     }
 
-    fn can_create_local_stream() -> bool {
-        P::can_create_local_stream()
+    fn local_can_open() -> bool {
+        P::local_can_open()
     }
 
-    fn close_stream_local_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
+    /// Open a new stream from the local side (i.e. as a Client).
+    //
+    fn local_open(&mut self, id: StreamId, sz: WindowSize) -> Result<(), ConnectionError> {
+        debug_assert!(Self::local_can_open());
+        assert!(Self::local_valid_id(id));
+        debug_assert!(!self.local_active.contains_key(&id));
+
+        self.local_active.insert(id, StreamState::Open {
+            remote: PeerState::Data(FlowControlState::with_initial_size(sz)),
+            local: PeerState::Headers,
+        });
+        Ok(())
+    }
+
+    /// Open a new stream from the remote side (i.e. as a Server).
+    fn remote_open(&mut self, id: StreamId, sz: WindowSize) -> Result<(), ConnectionError> {
+        debug_assert!(Self::remote_can_open());
+        assert!(Self::remote_valid_id(id));
+        debug_assert!(!self.remote_active.contains_key(&id));
+
+        self.remote_active.insert(id, StreamState::Open {
+            local: PeerState::Data(FlowControlState::with_initial_size(sz)),
+            remote: PeerState::Headers,
+        });
+        Ok(())
+    }
+
+    fn close_local_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
         let fully_closed = self.get_active_mut(id)
             .map(|s| s.close_local())
             .unwrap_or_else(|| Err(ProtocolError.into()))?;
@@ -163,7 +198,7 @@ impl<T, P: Peer> ControlStreams for StreamStore<T, P> {
         Ok(())
     }
 
-    fn close_stream_remote_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
+    fn close_remote_half(&mut self, id: StreamId) -> Result<(), ConnectionError> {
         let fully_closed = self.get_active_mut(id)
             .map(|s| s.close_remote())
             .unwrap_or_else(|| Err(ProtocolError.into()))?;
diff --git a/src/server.rs b/src/server.rs
index 96ad834..fac683a 100644
--- a/src/server.rs
+++ b/src/server.rs
@@ -118,7 +118,7 @@ impl Peer for Server {
         id.is_client_initiated()
     }
 
-    fn can_create_local_stream() -> bool {
+    fn local_can_open() -> bool {
         false
     }