diff --git a/resources/celerity/map.php b/resources/celerity/map.php
--- a/resources/celerity/map.php
+++ b/resources/celerity/map.php
@@ -412,9 +412,9 @@
     'rsrc/js/application/phortune/phortune-credit-card-form.js' => 'd12d214f',
     'rsrc/js/application/policy/behavior-policy-control.js' => '0eaa33a9',
     'rsrc/js/application/policy/behavior-policy-rule-editor.js' => '9347f172',
-    'rsrc/js/application/projects/WorkboardBoard.js' => '46573d65',
+    'rsrc/js/application/projects/WorkboardBoard.js' => '50147a89',
     'rsrc/js/application/projects/WorkboardCard.js' => '0392a5d8',
-    'rsrc/js/application/projects/WorkboardCardTemplate.js' => '2a61f8d4',
+    'rsrc/js/application/projects/WorkboardCardTemplate.js' => '84f82dad',
     'rsrc/js/application/projects/WorkboardColumn.js' => 'c3d24e63',
     'rsrc/js/application/projects/WorkboardController.js' => 'b9d0c2f3',
     'rsrc/js/application/projects/WorkboardDropEffect.js' => '8e0aa661',
@@ -743,9 +743,9 @@
     'javelin-view-renderer' => '9aae2b66',
     'javelin-view-visitor' => '308f9fe4',
     'javelin-websocket' => 'fdc13e4e',
-    'javelin-workboard-board' => '46573d65',
+    'javelin-workboard-board' => '50147a89',
     'javelin-workboard-card' => '0392a5d8',
-    'javelin-workboard-card-template' => '2a61f8d4',
+    'javelin-workboard-card-template' => '84f82dad',
     'javelin-workboard-column' => 'c3d24e63',
     'javelin-workboard-controller' => 'b9d0c2f3',
     'javelin-workboard-drop-effect' => '8e0aa661',
@@ -1133,9 +1133,6 @@
       'javelin-stratcom',
       'javelin-behavior',
     ),
-    '2a61f8d4' => array(
-      'javelin-install',
-    ),
     '2a8b62d9' => array(
       'multirow-row-manager',
       'javelin-install',
@@ -1292,18 +1289,6 @@
       'javelin-util',
       'phabricator-busy',
     ),
-    '46573d65' => array(
-      'javelin-install',
-      'javelin-dom',
-      'javelin-util',
-      'javelin-stratcom',
-      'javelin-workflow',
-      'phabricator-draggable-list',
-      'javelin-workboard-column',
-      'javelin-workboard-header-template',
-      'javelin-workboard-card-template',
-      'javelin-workboard-order-template',
-    ),
     '47a0728b' => array(
       'javelin-behavior',
       'javelin-dom',
@@ -1372,6 +1357,18 @@
     '4feea7d3' => array(
       'trigger-rule-control',
     ),
+    '50147a89' => array(
+      'javelin-install',
+      'javelin-dom',
+      'javelin-util',
+      'javelin-stratcom',
+      'javelin-workflow',
+      'phabricator-draggable-list',
+      'javelin-workboard-column',
+      'javelin-workboard-header-template',
+      'javelin-workboard-card-template',
+      'javelin-workboard-order-template',
+    ),
     '506aa3f4' => array(
       'javelin-behavior',
       'javelin-stratcom',
@@ -1619,6 +1616,9 @@
       'javelin-resource',
       'javelin-routable',
     ),
+    '84f82dad' => array(
+      'javelin-install',
+    ),
     '87428eb2' => array(
       'javelin-behavior',
       'javelin-diffusion-locate-file-source',
diff --git a/src/applications/project/controller/PhabricatorProjectBoardReloadController.php b/src/applications/project/controller/PhabricatorProjectBoardReloadController.php
--- a/src/applications/project/controller/PhabricatorProjectBoardReloadController.php
+++ b/src/applications/project/controller/PhabricatorProjectBoardReloadController.php
@@ -20,13 +20,42 @@
     $board_phid = $project->getPHID();
 
     $objects = $state->getObjects();
-    $object_phids = mpull($objects, 'getPHID');
+    $objects = mpull($objects, null, 'getPHID');
+
+    try {
+      $client_state = $request->getStr('state');
+      $client_state = phutil_json_decode($client_state);
+    } catch (PhutilJSONParserException $ex) {
+      $client_state = array();
+    }
+
+    // Figure out which objects need to be updated: either the client has an
+    // out-of-date version of them (objects which have been edited); or they
+    // exist on the client but not on the server (objects which have been
+    // removed from the board); or they exist on the server but not on the
+    // client (objects which have been added to the board).
+
+    $update_objects = array();
+    foreach ($objects as $object_phid => $object) {
+
+      // TODO: For now, this is always hard-coded.
+      $object_version = 2;
+
+      $client_version = idx($client_state, $object_phid, 0);
+      if ($object_version > $client_version) {
+        $update_objects[$object_phid] = $object;
+      }
+    }
+
+    $update_phids = array_keys($update_objects);
+    $visible_phids = array_keys($client_state);
 
     $engine = id(new PhabricatorBoardResponseEngine())
       ->setViewer($viewer)
       ->setBoardPHID($board_phid)
       ->setObjects($objects)
-      ->setUpdatePHIDs($object_phids);
+      ->setUpdatePHIDs($update_phids)
+      ->setVisiblePHIDs($visible_phids);
 
     // TODO: We don't currently process "order" properly. If a user is viewing
     // a board grouped by "Owner", and another user changes a task to be owned
diff --git a/webroot/rsrc/js/application/projects/WorkboardBoard.js b/webroot/rsrc/js/application/projects/WorkboardBoard.js
--- a/webroot/rsrc/js/application/projects/WorkboardBoard.js
+++ b/webroot/rsrc/js/application/projects/WorkboardBoard.js
@@ -734,7 +734,20 @@
     },
 
     _reloadCards: function() {
-      var data = {};
+      var state = {};
+
+      var columns = this.getColumns();
+      for (var column_phid in columns) {
+        var cards = columns[column_phid].getCards();
+        for (var card_phid in cards) {
+          state[card_phid] = this.getCardTemplate(card_phid).getVersion();
+        }
+      }
+
+      var data = {
+        state: JX.JSON.stringify(state),
+      };
+
       var on_reload = JX.bind(this, this._onReloadResponse);
 
       new JX.Request(this.getController().getReloadURI(), on_reload)
diff --git a/webroot/rsrc/js/application/projects/WorkboardCardTemplate.js b/webroot/rsrc/js/application/projects/WorkboardCardTemplate.js
--- a/webroot/rsrc/js/application/projects/WorkboardCardTemplate.js
+++ b/webroot/rsrc/js/application/projects/WorkboardCardTemplate.js
@@ -28,6 +28,11 @@
       return this._phid;
     },
 
+    getVersion: function() {
+      // TODO: For now, just return a constant version number.
+      return 1;
+    },
+
     setNodeHTMLTemplate: function(html) {
       this._html = html;
       return this;