diff --git a/matrix_bot_api/matrix_bot_api.py b/matrix_bot_api/matrix_bot_api.py
index 962fcc7..bc126d0 100644
--- a/matrix_bot_api/matrix_bot_api.py
+++ b/matrix_bot_api/matrix_bot_api.py
@@ -1,6 +1,7 @@
 import traceback
 import re
 from matrix_client.client import MatrixClient
+from matrix_client.room import Room
 from matrix_client.api import MatrixRequestError
 
 
@@ -10,7 +11,10 @@ class MatrixBotAPI:
     # password - Matrix password
     # server   - Matrix server url : port
     # rooms    - List of rooms ids to operate in, or None to accept all rooms
-    def __init__(self, username, password, server, rooms=None):
+    # exclusive_rooms - If True (the default), only the specified rooms will be
+    #            used, else they will simply be joined.
+    def __init__(self, username, password, server,
+                 rooms=None, exclusive_rooms=True):
         self.username = username
 
         # Authenticate with given credentials
@@ -25,25 +29,36 @@ def __init__(self, username, password, server, rooms=None):
             print("Invalid server URL")
             traceback.print_exc()
 
-        # Store allowed rooms
-        self.rooms = rooms
-
         # Store empty list of handlers
         self.handlers = []
 
         # If rooms is None, we should listen for invites and automatically accept them
         if rooms is None:
             self.client.add_invite_listener(self.handle_invite)
-            self.rooms = []
-
-            # Add all rooms we're currently in to self.rooms and add their callbacks
-            for room_id, room in self.client.get_rooms().items():
-                room.add_listener(self.handle_message)
-                self.rooms.append(room_id)
         else:
+            old_rooms = self.client.get_rooms()
+            new_rooms = []
             # Add the message callback for all specified rooms
-            for room in self.rooms:
-                room.add_listener(self.handle_message)
+            for room in rooms:
+                if isinstance(room, str):
+                    room = Room(self.client, room)
+                new_rooms.append(room)
+            # Remove existing rooms which were not specified explicitly
+            new_ids = [r.room_id for r in new_rooms]
+            if exclusive_rooms:
+                rooms_to_leave = []
+                for room_id, room in old_rooms.items():
+                    if not room_id in new_ids:
+                        rooms_to_leave.append(room)
+                for room in rooms_to_leave:
+                    room.leave()
+
+        # Store clean list of allowed rooms
+        self.rooms = []
+        # Add all rooms we're currently in to self.rooms and add their callbacks
+        for room_id, room in self.client.get_rooms().items():
+            room.add_listener(self.handle_message)
+            self.rooms.append(room_id)
 
     def add_handler(self, handler):
         self.handlers.append(handler)