diff --git a/src/java/com/threerings/crowd/server/CrowdClient.java b/src/java/com/threerings/crowd/server/CrowdClient.java
index b6d7db60d..4daca90f4 100644
--- a/src/java/com/threerings/crowd/server/CrowdClient.java
+++ b/src/java/com/threerings/crowd/server/CrowdClient.java
@@ -1,5 +1,5 @@
 //
-// $Id: CrowdClient.java,v 1.26 2004/10/01 22:04:18 mdb Exp $
+// $Id$
 //
 // Narya library - tools for developing networked games
 // Copyright (C) 2002-2004 Three Rings Design, Inc., All Rights Reserved
@@ -48,6 +48,15 @@ public class CrowdClient extends PresentsClient
         }
     }
 
+    // documentation inherited
+    protected void sessionWillStart ()
+    {
+        super.sessionWillStart();
+
+        // configure a specific access controller for the client object
+        _clobj.setAccessController(CrowdObjectAccess.USER);
+    }
+
     // documentation inherited
     protected void sessionWillResume ()
     {
diff --git a/src/java/com/threerings/crowd/server/CrowdObjectAccess.java b/src/java/com/threerings/crowd/server/CrowdObjectAccess.java
new file mode 100644
index 000000000..be4ec17ed
--- /dev/null
+++ b/src/java/com/threerings/crowd/server/CrowdObjectAccess.java
@@ -0,0 +1,106 @@
+//
+// $Id: YoObjectAccess.java 17796 2004-11-11 02:28:30Z mdb $
+//
+// Narya library - tools for developing networked games
+// Copyright (C) 2002-2004 Three Rings Design, Inc., All Rights Reserved
+// http://www.threerings.net/code/narya/
+//
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+package com.threerings.crowd.server;
+
+import com.threerings.presents.dobj.AccessController;
+import com.threerings.presents.dobj.DEvent;
+import com.threerings.presents.dobj.DObject;
+import com.threerings.presents.dobj.InvocationRequestEvent;
+import com.threerings.presents.dobj.MessageEvent;
+import com.threerings.presents.dobj.NamedEvent;
+import com.threerings.presents.dobj.Subscriber;
+
+import com.threerings.crowd.Log;
+import com.threerings.crowd.data.BodyObject;
+
+/**
+ * Defines the various object access controllers used by the Crowd server.
+ */
+public class CrowdObjectAccess
+{
+    /**
+     * Our default access controller. Disallows modification of any object
+     * but allows anyone to subscribe.
+     */
+    public static AccessController DEFAULT = new AccessController()
+    {
+        // documentation inherited from interface
+        public boolean allowSubscribe (DObject object, Subscriber subscriber)
+        {
+            // allow anyone to subscribe
+            return true;
+        }
+
+        // documentation inherited from interface
+        public boolean allowDispatch (DObject object, DEvent event)
+        {
+            // if the event came from the server, it's cool
+            if (event.getSourceOid() == -1) {
+                return true;
+
+            } else {
+                // if it came from the client, it better be a
+                // non-modification event
+                return (event instanceof MessageEvent ||
+                        event instanceof InvocationRequestEvent);
+            }
+        }
+    };
+
+    /**
+     * Provides access control for user objects.
+     */
+    public static AccessController USER = new AccessController()
+    {
+        // documentation inherited from interface
+        public boolean allowSubscribe (DObject object, Subscriber sub)
+        {
+            boolean allowed = true;
+            // if the subscriber is a client, ensure that they are this
+            // same user
+            if (sub instanceof CrowdClient) {
+                String cluser = ((CrowdClient)sub).getUsername().toString();
+                String obuser = ((BodyObject)object).username.toString();
+                allowed = obuser.equalsIgnoreCase(cluser);
+                if (!allowed) {
+                    Log.warning("Refusing BodyObject subscription request " +
+                                "[owner=" + obuser + ", sub=" + sub + "].");
+                }
+            }
+            return allowed;
+        }
+
+        // documentation inherited from interface
+        public boolean allowDispatch (DObject object, DEvent event)
+        {
+            // if the event came from the server, it's cool
+            if (event.getSourceOid() == -1) {
+                return true;
+
+            } else {
+                // the client is only allowed to modify the RECEIVERS field
+                return (event instanceof NamedEvent) &&
+                    ((NamedEvent)event).getName().equals(BodyObject.RECEIVERS);
+            }
+        }
+    };
+}
diff --git a/src/java/com/threerings/crowd/server/CrowdServer.java b/src/java/com/threerings/crowd/server/CrowdServer.java
index 54f3072b4..876255c89 100644
--- a/src/java/com/threerings/crowd/server/CrowdServer.java
+++ b/src/java/com/threerings/crowd/server/CrowdServer.java
@@ -57,6 +57,9 @@ public class CrowdServer extends PresentsServer
         // configure the client manager to use our resolver
         clmgr.setClientResolverClass(CrowdClientResolver.class);
 
+        // configure the dobject manager with our access controller
+        omgr.setDefaultAccessController(CrowdObjectAccess.DEFAULT);
+
         // create our place registry
         plreg = createPlaceRegistry(invmgr, omgr);