diff --git a/src/applications/project/__tests__/PhabricatorProjectCoreTestCase.php b/src/applications/project/__tests__/PhabricatorProjectCoreTestCase.php
--- a/src/applications/project/__tests__/PhabricatorProjectCoreTestCase.php
+++ b/src/applications/project/__tests__/PhabricatorProjectCoreTestCase.php
@@ -906,6 +906,165 @@
       $this->getTaskProjects($task));
   }
 
+  public function testBoardMoves() {
+    $user = $this->createUser();
+    $user->save();
+
+    $board = $this->createProject($user);
+
+    $backlog = $this->addColumn($user, $board, 0);
+    $column = $this->addColumn($user, $board, 1);
+
+    // New tasks should appear in the backlog.
+    $task1 = $this->newTask($user, array($board));
+    $expect = array(
+      $backlog->getPHID(),
+    );
+    $this->assertColumns($expect, $user, $board, $task1);
+
+    // Moving a task should move it to the destination column.
+    $this->moveToColumn($user, $board, $task1, $backlog, $column);
+    $expect = array(
+      $column->getPHID(),
+    );
+    $this->assertColumns($expect, $user, $board, $task1);
+
+    // Same thing again, with a new task.
+    $task2 = $this->newTask($user, array($board));
+    $expect = array(
+      $backlog->getPHID(),
+    );
+    $this->assertColumns($expect, $user, $board, $task2);
+
+    // Move it, too.
+    $this->moveToColumn($user, $board, $task2, $backlog, $column);
+    $expect = array(
+      $column->getPHID(),
+    );
+    $this->assertColumns($expect, $user, $board, $task2);
+
+    // Now the stuff should be in the column, in order, with the more recently
+    // moved task on top.
+    $expect = array(
+      $task2->getPHID(),
+      $task1->getPHID(),
+    );
+    $this->assertTasksInColumn($expect, $user, $board, $column);
+
+    // Move the second task after the first task.
+    $options = array(
+      'afterPHID' => $task1->getPHID(),
+    );
+    $this->moveToColumn($user, $board, $task2, $column, $column, $options);
+    $expect = array(
+      $task1->getPHID(),
+      $task2->getPHID(),
+    );
+    $this->assertTasksInColumn($expect, $user, $board, $column);
+
+    // Move the second task before the first task.
+    $options = array(
+      'beforePHID' => $task1->getPHID(),
+    );
+    $this->moveToColumn($user, $board, $task2, $column, $column, $options);
+    $expect = array(
+      $task2->getPHID(),
+      $task1->getPHID(),
+    );
+    $this->assertTasksInColumn($expect, $user, $board, $column);
+
+  }
+
+  private function moveToColumn(
+    PhabricatorUser $viewer,
+    PhabricatorProject $board,
+    ManiphestTask $task,
+    PhabricatorProjectColumn $src,
+    PhabricatorProjectColumn $dst,
+    $options = null) {
+
+    $xactions = array();
+
+    if (!$options) {
+      $options = array();
+    }
+
+    $xactions[] = id(new ManiphestTransaction())
+      ->setTransactionType(ManiphestTransaction::TYPE_PROJECT_COLUMN)
+      ->setOldValue(
+        array(
+          'projectPHID' => $board->getPHID(),
+          'columnPHIDs' => array($src->getPHID()),
+        ))
+      ->setNewValue(
+        array(
+          'projectPHID' => $board->getPHID(),
+          'columnPHIDs' => array($dst->getPHID()),
+        ) + $options);
+
+    $editor = id(new ManiphestTransactionEditor())
+      ->setActor($viewer)
+      ->setContentSource(PhabricatorContentSource::newConsoleSource())
+      ->setContinueOnNoEffect(true)
+      ->applyTransactions($task, $xactions);
+  }
+
+  private function assertColumns(
+    array $expect,
+    PhabricatorUser $viewer,
+    PhabricatorProject $board,
+    ManiphestTask $task) {
+
+    $engine = id(new PhabricatorBoardLayoutEngine())
+      ->setViewer($viewer)
+      ->setBoardPHIDs(array($board->getPHID()))
+      ->setObjectPHIDs(
+        array(
+          $task->getPHID(),
+        ))
+      ->executeLayout();
+
+    $columns = $engine->getObjectColumns($board->getPHID(), $task->getPHID());
+    $column_phids = mpull($columns, 'getPHID');
+    $column_phids = array_values($column_phids);
+
+    $this->assertEqual($expect, $column_phids);
+  }
+
+  private function assertTasksInColumn(
+    array $expect,
+    PhabricatorUser $viewer,
+    PhabricatorProject $board,
+    PhabricatorProjectColumn $column) {
+
+    $engine = id(new PhabricatorBoardLayoutEngine())
+      ->setViewer($viewer)
+      ->setBoardPHIDs(array($board->getPHID()))
+      ->setObjectPHIDs($expect)
+      ->executeLayout();
+
+    $object_phids = $engine->getColumnObjectPHIDs(
+      $board->getPHID(),
+      $column->getPHID());
+    $object_phids = array_values($object_phids);
+
+    $this->assertEqual($expect, $object_phids);
+  }
+
+  private function addColumn(
+    PhabricatorUser $viewer,
+    PhabricatorProject $project,
+    $sequence) {
+
+    $project->setHasWorkboard(1)->save();
+
+    return PhabricatorProjectColumn::initializeNewColumn($viewer)
+      ->setSequence(0)
+      ->setProperty('isDefault', ($sequence == 0))
+      ->setProjectPHID($project->getPHID())
+      ->save();
+  }
+
   private function getTaskProjects(ManiphestTask $task) {
     $project_phids = PhabricatorEdgeQuery::loadDestinationPHIDs(
       $task->getPHID(),
diff --git a/src/applications/project/engine/PhabricatorBoardLayoutEngine.php b/src/applications/project/engine/PhabricatorBoardLayoutEngine.php
--- a/src/applications/project/engine/PhabricatorBoardLayoutEngine.php
+++ b/src/applications/project/engine/PhabricatorBoardLayoutEngine.php
@@ -23,7 +23,7 @@
   }
 
   public function setBoardPHIDs(array $board_phids) {
-    $this->boardPHIDs = $board_phids;
+    $this->boardPHIDs = array_fuse($board_phids);
     return $this;
   }
 
@@ -32,7 +32,7 @@
   }
 
   public function setObjectPHIDs(array $object_phids) {
-    $this->objectPHIDs = $object_phids;
+    $this->objectPHIDs = array_fuse($object_phids);
     return $this;
   }