diff --git a/classes/Notice.php b/classes/Notice.php
index 114119bfc9..83507f3bc0 100644
--- a/classes/Notice.php
+++ b/classes/Notice.php
@@ -73,6 +73,7 @@ class Notice extends Memcached_DataObject
     public $location_ns;                     // int(4)
     public $repeat_of;                       // int(4)
     public $object_type;                     // varchar(255)
+    public $scope;                           // int(4)
 
     /* Static get */
     function staticGet($k,$v=NULL)
@@ -89,6 +90,11 @@ class Notice extends Memcached_DataObject
     const LOCAL_NONPUBLIC = -1;
     const GATEWAY         = -2;
 
+    const SITE_SCOPE      = 1;
+    const ADDRESSEE_SCOPE = 2;
+    const GROUP_SCOPE     = 4;
+    const FOLLOWER_SCOPE  = 8;
+
     function getProfile()
     {
         $profile = Profile::staticGet('id', $this->profile_id);
@@ -2011,4 +2017,84 @@ class Notice extends Memcached_DataObject
                     ($this->is_local != Notice::GATEWAY));
         }
     }
+
+    /**
+     * Check that the given profile is allowed to read, respond to, or otherwise
+     * act on this notice.
+     * 
+     * The $scope member is a bitmask of scopes, representing a logical AND of the
+     * scope requirement. So, 0x03 (Notice::ADDRESSEE_SCOPE | Notice::SITE_SCOPE) means
+     * "only visible to people who are mentioned in the notice AND are users on this site."
+     * Users on the site who are not mentioned in the notice will not be able to see the
+     * notice.
+     *
+     * @param Profile $profile The profile to check
+     *
+     * @return boolean whether the profile is in the notice's scope
+     */
+
+    function inScope($profile)
+    {
+        // If there's any scope, and there's no logged-in user,
+        // not allowed.
+
+        if ($this->scope > 0 && empty($profile)) {
+            return false;
+        }
+
+        // Only for users on this site
+
+        if ($this->scope & Notice::SITE_SCOPE) {
+            $user = $profile->getUser();
+            if (empty($user)) {
+                return false;
+            }
+        }
+
+        // Only for users mentioned in the notice
+
+        if ($this->scope & Notice::ADDRESSEE_SCOPE) {
+
+            // XXX: just query for the single reply
+
+            $replies = $this->getReplies();
+
+            if (!in_array($profile->id, $replies)) {
+                return false;
+            }
+        }
+
+        // Only for members of the given group
+
+        if ($this->scope & Notice::GROUP_SCOPE) {
+
+            // XXX: just query for the single membership
+
+            $groups = $this->getGroups();
+
+            $foundOne = false;
+
+            foreach ($groups as $group) {
+                if ($profile->isMember($group)) {
+                    $foundOne = true;
+                    break;
+                }
+            }
+
+            if (!$foundOne) {
+                return false;
+            }
+        }
+
+        // Only for followers of the author
+
+        if ($this->scope & Notice::FOLLOWER_SCOPE) {
+            $author = $this->getProfile();
+            if (!Subscription::exists($profile, $author)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
 }
diff --git a/classes/Profile.php b/classes/Profile.php
index b582451350..b6b05f6a4f 100644
--- a/classes/Profile.php
+++ b/classes/Profile.php
@@ -1090,4 +1090,44 @@ class Profile extends Memcached_DataObject
 
         return $profile;
     }
+
+    function canRead(Notice $notice)
+    {
+        if ($notice->scope & Notice::SITE_SCOPE) {
+            $user = $this->getUser();
+            if (empty($user)) {
+                return false;
+            }
+        }
+
+        if ($notice->scope & Notice::ADDRESSEE_SCOPE) {
+            $replies = $notice->getReplies();
+
+            if (!in_array($this->id, $replies)) {
+                $groups = $notice->getGroups();
+
+                $foundOne = false;
+
+                foreach ($groups as $group) {
+                    if ($this->isMember($group)) {
+                        $foundOne = true;
+                        break;
+                    }
+                }
+
+                if (!$foundOne) {
+                    return false;
+                }
+            }
+        }
+
+        if ($notice->scope & Notice::FOLLOWER_SCOPE) {
+            $author = $notice->getProfile();
+            if (!Subscription::exists($this, $author)) {
+                return false;
+            }
+        }
+
+        return true;
+    }
 }
diff --git a/classes/statusnet.ini b/classes/statusnet.ini
index f648fb3fbf..12c59daae0 100644
--- a/classes/statusnet.ini
+++ b/classes/statusnet.ini
@@ -337,6 +337,7 @@ location_id = 1
 location_ns = 1
 repeat_of = 1
 object_type = 2
+scope = 1
 
 [notice__keys]
 id = N
diff --git a/db/core.php b/db/core.php
index 928186d94d..3e439e5010 100644
--- a/db/core.php
+++ b/db/core.php
@@ -202,6 +202,9 @@ $schema['notice'] = array(
         'location_ns' => array('type' => 'int', 'description' => 'namespace for location'),
         'repeat_of' => array('type' => 'int', 'description' => 'notice this is a repeat of'),
         'object_type' => array('type' => 'varchar', 'length' => 255, 'description' => 'URI representing activity streams object type', 'default' => 'http://activitystrea.ms/schema/1.0/note'),
+        'scope' => array('type' => 'int',
+                         'default' => '1',
+                         'description' => 'bit map for distribution scope; 0 = everywhere; 1 = this server only; 2 = addressees; 4 = followers'),
     ),
     'primary key' => array('id'),
     'unique keys' => array(