diff --git a/IPython/frontend/qt/base_frontend_mixin.py b/IPython/frontend/qt/base_frontend_mixin.py
index 02080b7..c4189d3 100644
--- a/IPython/frontend/qt/base_frontend_mixin.py
+++ b/IPython/frontend/qt/base_frontend_mixin.py
@@ -96,7 +96,7 @@ class BaseFrontendMixin(object):
         """ Calls the frontend handler associated with the message type of the 
             given message.
         """
-        msg_type = msg['msg_type']
+        msg_type = msg['header']['msg_type']
         handler = getattr(self, '_handle_' + msg_type, None)
         if handler:
             handler(msg)
diff --git a/IPython/frontend/qt/kernelmanager.py b/IPython/frontend/qt/kernelmanager.py
index c6a5dde..f243114 100644
--- a/IPython/frontend/qt/kernelmanager.py
+++ b/IPython/frontend/qt/kernelmanager.py
@@ -66,7 +66,7 @@ class QtShellSocketChannel(SocketChannelQObject, ShellSocketChannel):
         self.message_received.emit(msg)
         
         # Emit signals for specialized message types.
-        msg_type = msg['msg_type']
+        msg_type = msg['header']['msg_type']
         signal = getattr(self, msg_type, None)
         if signal:
             signal.emit(msg)
@@ -122,7 +122,7 @@ class QtSubSocketChannel(SocketChannelQObject, SubSocketChannel):
         # Emit the generic signal.
         self.message_received.emit(msg)
         # Emit signals for specialized message types.
-        msg_type = msg['msg_type']
+        msg_type = msg['header']['msg_type']
         signal = getattr(self, msg_type + '_received', None)
         if signal:
             signal.emit(msg)
@@ -155,7 +155,7 @@ class QtStdInSocketChannel(SocketChannelQObject, StdInSocketChannel):
         self.message_received.emit(msg)
         
         # Emit signals for specialized message types.
-        msg_type = msg['msg_type']
+        msg_type = msg['header']['msg_type']
         if msg_type == 'input_request':
             self.input_requested.emit(msg)
 
diff --git a/IPython/parallel/client/client.py b/IPython/parallel/client/client.py
index 60cbd67..3d3975d 100644
--- a/IPython/parallel/client/client.py
+++ b/IPython/parallel/client/client.py
@@ -670,7 +670,7 @@ class Client(HasTraits):
         while msg is not None:
             if self.debug:
                 pprint(msg)
-            msg_type = msg['msg_type']
+            msg_type = msg['header']['msg_type']
             handler = self._notification_handlers.get(msg_type, None)
             if handler is None:
                 raise Exception("Unhandled message type: %s"%msg.msg_type)
@@ -684,7 +684,7 @@ class Client(HasTraits):
         while msg is not None:
             if self.debug:
                 pprint(msg)
-            msg_type = msg['msg_type']
+            msg_type = msg['header']['msg_type']
             handler = self._queue_handlers.get(msg_type, None)
             if handler is None:
                 raise Exception("Unhandled message type: %s"%msg.msg_type)
@@ -729,7 +729,7 @@ class Client(HasTraits):
             msg_id = parent['msg_id']
             content = msg['content']
             header = msg['header']
-            msg_type = msg['msg_type']
+            msg_type = msg['header']['msg_type']
             
             # init metadata:
             md = self.metadata[msg_id]
@@ -994,7 +994,7 @@ class Client(HasTraits):
         msg = self.session.send(socket, "apply_request", buffers=bufs, ident=ident,
                             subheader=subheader, track=track)
         
-        msg_id = msg['msg_id']
+        msg_id = msg['header']['msg_id']
         self.outstanding.add(msg_id)
         if ident:
             # possibly routed to a specific engine
diff --git a/IPython/parallel/client/view.py b/IPython/parallel/client/view.py
index 12ed96d..1b1eae6 100644
--- a/IPython/parallel/client/view.py
+++ b/IPython/parallel/client/view.py
@@ -523,7 +523,7 @@ class DirectView(View):
                                     ident=ident)
             if track:
                 trackers.append(msg['tracker'])
-            msg_ids.append(msg['msg_id'])
+            msg_ids.append(msg['header']['msg_id'])
         tracker = None if track is False else zmq.MessageTracker(*trackers)
         ar = AsyncResult(self.client, msg_ids, fname=f.__name__, targets=targets, tracker=tracker)
         if block:
@@ -980,7 +980,7 @@ class LoadBalancedView(View):
                                 subheader=subheader)
         tracker = None if track is False else msg['tracker']
         
-        ar = AsyncResult(self.client, msg['msg_id'], fname=f.__name__, targets=None, tracker=tracker)
+        ar = AsyncResult(self.client, msg['header']['msg_id'], fname=f.__name__, targets=None, tracker=tracker)
         
         if block:
             try:
diff --git a/IPython/parallel/controller/hub.py b/IPython/parallel/controller/hub.py
index 5a66178..a82acc9 100755
--- a/IPython/parallel/controller/hub.py
+++ b/IPython/parallel/controller/hub.py
@@ -494,7 +494,7 @@ class Hub(SessionFactory):
             return
         # print client_id, header, parent, content
         #switch on message type:
-        msg_type = msg['msg_type']
+        msg_type = msg['header']['msg_type']
         self.log.info("client::client %r requested %r"%(client_id, msg_type))
         handler = self.query_handlers.get(msg_type, None)
         try:
@@ -791,7 +791,7 @@ class Hub(SessionFactory):
             self.log.error("iopub::invalid IOPub message: %r"%msg)
             return
         msg_id = parent['msg_id']
-        msg_type = msg['msg_type']
+        msg_type = msg['header']['msg_type']
         content = msg['content']
         
         # ensure msg_id is in db
diff --git a/IPython/parallel/controller/scheduler.py b/IPython/parallel/controller/scheduler.py
index 747d5b6..db4bb74 100644
--- a/IPython/parallel/controller/scheduler.py
+++ b/IPython/parallel/controller/scheduler.py
@@ -216,7 +216,7 @@ class TaskScheduler(SessionFactory):
             self.log.warn("task::Unauthorized message from: %r"%idents)
             return
         
-        msg_type = msg['msg_type']
+        msg_type = msg['header']['msg_type']
         
         handler = self._notification_handlers.get(msg_type, None)
         if handler is None:
diff --git a/IPython/parallel/engine/kernelstarter.py b/IPython/parallel/engine/kernelstarter.py
index fe92d1d..196434d 100644
--- a/IPython/parallel/engine/kernelstarter.py
+++ b/IPython/parallel/engine/kernelstarter.py
@@ -44,7 +44,7 @@ class KernelStarter(object):
         except:
             print ("bad msg: %s"%msg)
         
-        msgtype = msg['msg_type']
+        msgtype = msg['header']['msg_type']
         handler = self.handlers.get(msgtype, None)
         if handler is None:
             self.downstream.send_multipart(raw_msg, copy=False)
@@ -58,7 +58,7 @@ class KernelStarter(object):
         except:
             print ("bad msg: %s"%msg)
         
-        msgtype = msg['msg_type']
+        msgtype = msg['header']['msg_type']
         handler = self.handlers.get(msgtype, None)
         if handler is None:
             self.upstream.send_multipart(raw_msg, copy=False)
@@ -227,4 +227,4 @@ def make_starter(up_addr, down_addr, *args, **kwargs):
     starter = KernelStarter(session, upstream, downstream, *args, **kwargs)
     starter.start()
     loop.start()
-    
\ No newline at end of file
+    
diff --git a/IPython/parallel/engine/streamkernel.py b/IPython/parallel/engine/streamkernel.py
index 5e6203b..579a2fb 100755
--- a/IPython/parallel/engine/streamkernel.py
+++ b/IPython/parallel/engine/streamkernel.py
@@ -150,7 +150,7 @@ class Kernel(SessionFactory):
                 
             self.log.info("Aborting:")
             self.log.info(str(msg))
-            msg_type = msg['msg_type']
+            msg_type = msg['header']['msg_type']
             reply_type = msg_type.split('_')[0] + '_reply'
             # reply_msg = self.session.msg(reply_type, {'status' : 'aborted'}, msg)
             # self.reply_socket.send(ident,zmq.SNDMORE)
@@ -205,9 +205,9 @@ class Kernel(SessionFactory):
         header = msg['header']
         msg_id = header['msg_id']
         
-        handler = self.control_handlers.get(msg['msg_type'], None)
+        handler = self.control_handlers.get(msg['header']['msg_type'], None)
         if handler is None:
-            self.log.error("UNKNOWN CONTROL MESSAGE TYPE: %r"%msg['msg_type'])
+            self.log.error("UNKNOWN CONTROL MESSAGE TYPE: %r"%msg['header']['msg_type'])
         else:
             handler(self.control_stream, idents, msg)
     
@@ -386,14 +386,14 @@ class Kernel(SessionFactory):
         if self.check_aborted(msg_id):
             self.aborted.remove(msg_id)
             # is it safe to assume a msg_id will not be resubmitted?
-            reply_type = msg['msg_type'].split('_')[0] + '_reply'
+            reply_type = msg['header']['msg_type'].split('_')[0] + '_reply'
             status = {'status' : 'aborted'}
             reply_msg = self.session.send(stream, reply_type, subheader=status,
                         content=status, parent=msg, ident=idents)
             return
-        handler = self.shell_handlers.get(msg['msg_type'], None)
+        handler = self.shell_handlers.get(msg['header']['msg_type'], None)
         if handler is None:
-            self.log.error("UNKNOWN MESSAGE TYPE: %r"%msg['msg_type'])
+            self.log.error("UNKNOWN MESSAGE TYPE: %r"%msg['header']['msg_type'])
         else:
             handler(stream, idents, msg)
     
diff --git a/IPython/parallel/tests/test_db.py b/IPython/parallel/tests/test_db.py
index fddb961..f9c08d5 100644
--- a/IPython/parallel/tests/test_db.py
+++ b/IPython/parallel/tests/test_db.py
@@ -56,8 +56,8 @@ class TestDictBackend(TestCase):
             msg = self.session.msg('apply_request', content=dict(a=5))
             msg['buffers'] = []
             rec = init_record(msg)
-            msg_ids.append(msg['msg_id'])
-            self.db.add_record(msg['msg_id'], rec)
+            msg_ids.append(msg['header']['msg_id'])
+            self.db.add_record(msg['header']['msg_id'], rec)
         return msg_ids
     
     def test_add_record(self):
diff --git a/IPython/zmq/ipkernel.py b/IPython/zmq/ipkernel.py
index 3b47f6a..fb58d29 100755
--- a/IPython/zmq/ipkernel.py
+++ b/IPython/zmq/ipkernel.py
@@ -133,11 +133,11 @@ class Kernel(Configurable):
         # Print some info about this message and leave a '--->' marker, so it's
         # easier to trace visually the message chain when debugging.  Each
         # handler prints its message at the end.
-        self.log.debug('\n*** MESSAGE TYPE:'+str(msg['msg_type'])+'***')
+        self.log.debug('\n*** MESSAGE TYPE:'+str(msg['header']['msg_type'])+'***')
         self.log.debug('   Content: '+str(msg['content'])+'\n   --->\n   ')
 
         # Find and call actual handler for message
-        handler = self.handlers.get(msg['msg_type'], None)
+        handler = self.handlers.get(msg['header']['msg_type'], None)
         if handler is None:
             self.log.error("UNKNOWN MESSAGE TYPE:" +str(msg))
         else:
@@ -375,7 +375,7 @@ class Kernel(Configurable):
                        "Unexpected missing message part."
 
             self.log.debug("Aborting:\n"+str(Message(msg)))
-            msg_type = msg['msg_type']
+            msg_type = msg['header']['msg_type']
             reply_type = msg_type.split('_')[0] + '_reply'
             reply_msg = self.session.send(self.shell_socket, reply_type,
                     {'status' : 'aborted'}, msg, ident=ident)
diff --git a/IPython/zmq/pykernel.py b/IPython/zmq/pykernel.py
index fb62629..42835da 100755
--- a/IPython/zmq/pykernel.py
+++ b/IPython/zmq/pykernel.py
@@ -190,7 +190,7 @@ class Kernel(HasTraits):
             else:
                 assert ident is not None, "Missing message part."
             self.log.debug("Aborting: %s"%Message(msg))
-            msg_type = msg['msg_type']
+            msg_type = msg['header']['msg_type']
             reply_type = msg_type.split('_')[0] + '_reply'
             reply_msg = self.session.send(self.shell_socket, reply_type, {'status':'aborted'}, msg, ident=ident)
             self.log.debug(Message(reply_msg))
diff --git a/IPython/zmq/session.py b/IPython/zmq/session.py
index 7d2ebc9..c504986 100644
--- a/IPython/zmq/session.py
+++ b/IPython/zmq/session.py
@@ -359,9 +359,7 @@ class Session(Configurable):
         """
         msg = {}
         msg['header'] = self.msg_header(msg_type)
-        msg['msg_id'] = msg['header']['msg_id']
         msg['parent_header'] = {} if parent is None else extract_header(parent)
-        msg['msg_type'] = msg_type
         msg['content'] = {} if content is None else content
         sub = {} if subheader is None else subheader
         msg['header'].update(sub)
@@ -651,7 +649,6 @@ class Session(Configurable):
         if not len(msg_list) >= minlen:
             raise TypeError("malformed message, must have at least %i elements"%minlen)
         message['header'] = self.unpack(msg_list[1])
-        message['msg_type'] = message['header']['msg_type']
         message['parent_header'] = self.unpack(msg_list[2])
         if content:
             message['content'] = self.unpack(msg_list[3])
diff --git a/IPython/zmq/tests/test_session.py b/IPython/zmq/tests/test_session.py
index 6279acc..86badca 100644
--- a/IPython/zmq/tests/test_session.py
+++ b/IPython/zmq/tests/test_session.py
@@ -37,10 +37,8 @@ class TestSession(SessionTestCase):
         self.assertTrue(isinstance(msg['content'],dict))
         self.assertTrue(isinstance(msg['header'],dict))
         self.assertTrue(isinstance(msg['parent_header'],dict))
-        self.assertEquals(msg['msg_type'], 'execute')
+        self.assertEquals(msg['header']['msg_type'], 'execute')
         
-            
-    
     def test_args(self):
         """initialization arguments for Session"""
         s = self.session