diff --git a/resources/celerity/map.php b/resources/celerity/map.php
index 586e568f64..972a5c2b56 100644
--- a/resources/celerity/map.php
+++ b/resources/celerity/map.php
@@ -409,7 +409,7 @@ return array(
     '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' => '223af34e',
+    'rsrc/js/application/projects/WorkboardBoard.js' => '106d870f',
     'rsrc/js/application/projects/WorkboardCard.js' => '0392a5d8',
     'rsrc/js/application/projects/WorkboardCardTemplate.js' => '2a61f8d4',
     'rsrc/js/application/projects/WorkboardColumn.js' => 'c3d24e63',
@@ -737,7 +737,7 @@ return array(
     'javelin-view-renderer' => '9aae2b66',
     'javelin-view-visitor' => '308f9fe4',
     'javelin-websocket' => 'fdc13e4e',
-    'javelin-workboard-board' => '223af34e',
+    'javelin-workboard-board' => '106d870f',
     'javelin-workboard-card' => '0392a5d8',
     'javelin-workboard-card-template' => '2a61f8d4',
     'javelin-workboard-column' => 'c3d24e63',
@@ -1015,6 +1015,18 @@ return array(
       'javelin-workflow',
       'phuix-icon-view',
     ),
+    '106d870f' => 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',
+    ),
     '111bfd2d' => array(
       'javelin-install',
     ),
@@ -1073,18 +1085,6 @@ return array(
       'javelin-behavior',
       'javelin-request',
     ),
-    '223af34e' => 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',
-    ),
     '225bbb98' => array(
       'javelin-install',
       'javelin-reactor',
diff --git a/src/applications/maniphest/editor/ManiphestEditEngine.php b/src/applications/maniphest/editor/ManiphestEditEngine.php
index 76c2276df0..2a8730d5c6 100644
--- a/src/applications/maniphest/editor/ManiphestEditEngine.php
+++ b/src/applications/maniphest/editor/ManiphestEditEngine.php
@@ -123,22 +123,23 @@ information about the move, including an optional specific position within the
 column.
 
 The target column should be identified as `columnPHID`, and you may select a
-position by passing either `beforePHID` or `afterPHID`, specifying the PHID of
-a task currently in the column that you want to move this task before or after:
+position by passing either `beforePHIDs` or `afterPHIDs`, specifying the PHIDs
+of tasks currently in the column that you want to move this task before or
+after:
 
 ```lang=json
 [
   {
     "columnPHID": "PHID-PCOL-4444",
-    "beforePHID": "PHID-TASK-5555"
+    "beforePHIDs": ["PHID-TASK-5555"]
   }
 ]
 ```
 
-Note that this affects only the "natural" position of the task. The task
-position when the board is sorted by some other attribute (like priority)
-depends on that attribute value: change a task's priority to move it on
-priority-sorted boards.
+When you specify multiple PHIDs, the task will be moved adjacent to the first
+valid PHID found in either of the lists. This allows positional moves to
+generally work as users expect even if the client view of the board has fallen
+out of date and some of the nearby tasks have moved elsewhere.
 EODOCS
       );
 
diff --git a/src/applications/maniphest/editor/ManiphestTransactionEditor.php b/src/applications/maniphest/editor/ManiphestTransactionEditor.php
index 5cb7cf91ba..5198f44572 100644
--- a/src/applications/maniphest/editor/ManiphestTransactionEditor.php
+++ b/src/applications/maniphest/editor/ManiphestTransactionEditor.php
@@ -428,6 +428,7 @@ final class ManiphestTransactionEditor
   private function buildMoveTransaction(
     PhabricatorLiskDAO $object,
     PhabricatorApplicationTransaction $xaction) {
+    $actor = $this->getActor();
 
     $new = $xaction->getNewValue();
     if (!is_array($new)) {
@@ -435,7 +436,7 @@ final class ManiphestTransactionEditor
       $new = array($new);
     }
 
-    $nearby_phids = array();
+    $relative_phids = array();
     foreach ($new as $key => $value) {
       if (!is_array($value)) {
         $this->validateColumnPHID($value);
@@ -448,35 +449,83 @@ final class ManiphestTransactionEditor
         $value,
         array(
           'columnPHID' => 'string',
+          'beforePHIDs' => 'optional list<string>',
+          'afterPHIDs' => 'optional list<string>',
+
+          // Deprecated older variations of "beforePHIDs" and "afterPHIDs".
           'beforePHID' => 'optional string',
           'afterPHID' => 'optional string',
         ));
 
-      $new[$key] = $value;
-
-      if (!empty($value['beforePHID'])) {
-        $nearby_phids[] = $value['beforePHID'];
-      }
+      $value = $value + array(
+        'beforePHIDs' => array(),
+        'afterPHIDs' => array(),
+      );
 
+      // Normalize the legacy keys "beforePHID" and "afterPHID" keys to the
+      // modern format.
       if (!empty($value['afterPHID'])) {
-        $nearby_phids[] = $value['afterPHID'];
+        if ($value['afterPHIDs']) {
+          throw new Exception(
+            pht(
+              'Transaction specifies both "afterPHID" and "afterPHIDs". '.
+              'Specify only "afterPHIDs".'));
+        }
+        $value['afterPHIDs'] = array($value['afterPHID']);
+        unset($value['afterPHID']);
       }
+
+      if (isset($value['beforePHID'])) {
+        if ($value['beforePHIDs']) {
+          throw new Exception(
+            pht(
+              'Transaction specifies both "beforePHID" and "beforePHIDs". '.
+              'Specify only "beforePHIDs".'));
+        }
+        $value['beforePHIDs'] = array($value['beforePHID']);
+        unset($value['beforePHID']);
+      }
+
+      foreach ($value['beforePHIDs'] as $phid) {
+        $relative_phids[] = $phid;
+      }
+
+      foreach ($value['afterPHIDs'] as $phid) {
+        $relative_phids[] = $phid;
+      }
+
+      $new[$key] = $value;
     }
 
-    if ($nearby_phids) {
-      $nearby_objects = id(new PhabricatorObjectQuery())
-        ->setViewer($this->getActor())
-        ->withPHIDs($nearby_phids)
+    // We require that objects you specify in "beforePHIDs" or "afterPHIDs"
+    // are real objects which exist and which you have permission to view.
+    // If you provide other objects, we remove them from the specification.
+
+    if ($relative_phids) {
+      $objects = id(new PhabricatorObjectQuery())
+        ->setViewer($actor)
+        ->withPHIDs($relative_phids)
         ->execute();
-      $nearby_objects = mpull($nearby_objects, null, 'getPHID');
+      $objects = mpull($objects, null, 'getPHID');
     } else {
-      $nearby_objects = array();
+      $objects = array();
+    }
+
+    foreach ($new as $key => $value) {
+      $value['afterPHIDs'] = $this->filterValidPHIDs(
+        $value['afterPHIDs'],
+        $objects);
+      $value['beforePHIDs'] = $this->filterValidPHIDs(
+        $value['beforePHIDs'],
+        $objects);
+
+      $new[$key] = $value;
     }
 
     $column_phids = ipull($new, 'columnPHID');
     if ($column_phids) {
       $columns = id(new PhabricatorProjectColumnQuery())
-        ->setViewer($this->getActor())
+        ->setViewer($actor)
         ->withPHIDs($column_phids)
         ->execute();
       $columns = mpull($columns, null, 'getPHID');
@@ -487,10 +536,9 @@ final class ManiphestTransactionEditor
     $board_phids = mpull($columns, 'getProjectPHID');
     $object_phid = $object->getPHID();
 
-    $object_phids = $nearby_phids;
-
     // Note that we may not have an object PHID if we're creating a new
     // object.
+    $object_phids = array();
     if ($object_phid) {
       $object_phids[] = $object_phid;
     }
@@ -517,49 +565,6 @@ final class ManiphestTransactionEditor
 
       $board_phid = $column->getProjectPHID();
 
-      $nearby = array();
-
-      if (!empty($spec['beforePHID'])) {
-        $nearby['beforePHID'] = $spec['beforePHID'];
-      }
-
-      if (!empty($spec['afterPHID'])) {
-        $nearby['afterPHID'] = $spec['afterPHID'];
-      }
-
-      if (count($nearby) > 1) {
-        throw new Exception(
-          pht(
-            'Column move transaction moves object to multiple positions. '.
-            'Specify only "beforePHID" or "afterPHID", not both.'));
-      }
-
-      foreach ($nearby as $where => $nearby_phid) {
-        if (empty($nearby_objects[$nearby_phid])) {
-          throw new Exception(
-            pht(
-              'Column move transaction specifies object "%s" as "%s", but '.
-              'there is no corresponding object with this PHID.',
-              $object_phid,
-              $where));
-        }
-
-        $nearby_columns = $layout_engine->getObjectColumns(
-          $board_phid,
-          $nearby_phid);
-        $nearby_columns = mpull($nearby_columns, null, 'getPHID');
-
-        if (empty($nearby_columns[$column_phid])) {
-          throw new Exception(
-            pht(
-              'Column move transaction specifies object "%s" as "%s" in '.
-              'column "%s", but this object is not in that column!',
-              $nearby_phid,
-              $where,
-              $column_phid));
-        }
-      }
-
       if ($object_phid) {
         $old_columns = $layout_engine->getObjectColumns(
           $board_phid,
@@ -578,8 +583,8 @@ final class ManiphestTransactionEditor
       // We can just drop this column change if it has no effect.
       $from_map = array_fuse($spec['fromColumnPHIDs']);
       $already_here = isset($from_map[$column_phid]);
-      $is_reordering = (bool)$nearby;
 
+      $is_reordering = ($spec['afterPHIDs'] || $spec['beforePHIDs']);
       if ($already_here && !$is_reordering) {
         unset($new[$key]);
       } else {
@@ -677,8 +682,9 @@ final class ManiphestTransactionEditor
   private function applyBoardMove($object, array $move) {
     $board_phid = $move['boardPHID'];
     $column_phid = $move['columnPHID'];
-    $before_phid = idx($move, 'beforePHID');
-    $after_phid = idx($move, 'afterPHID');
+
+    $before_phids = $move['beforePHIDs'];
+    $after_phids = $move['afterPHIDs'];
 
     $object_phid = $object->getPHID();
 
@@ -730,24 +736,12 @@ final class ManiphestTransactionEditor
         $object_phid);
     }
 
-    if ($before_phid) {
-      $engine->queueAddPositionBefore(
-        $board_phid,
-        $column_phid,
-        $object_phid,
-        $before_phid);
-    } else if ($after_phid) {
-      $engine->queueAddPositionAfter(
-        $board_phid,
-        $column_phid,
-        $object_phid,
-        $after_phid);
-    } else {
-      $engine->queueAddPosition(
-        $board_phid,
-        $column_phid,
-        $object_phid);
-    }
+    $engine->queueAddPosition(
+      $board_phid,
+      $column_phid,
+      $object_phid,
+      $after_phids,
+      $before_phids);
 
     $engine->applyPositionUpdates();
   }
@@ -849,4 +843,16 @@ final class ManiphestTransactionEditor
     return $errors;
   }
 
+  private function filterValidPHIDs($phid_list, array $object_map) {
+    foreach ($phid_list as $key => $phid) {
+      if (isset($object_map[$phid])) {
+        continue;
+      }
+
+      unset($phid_list[$key]);
+    }
+
+    return array_values($phid_list);
+  }
+
 }
diff --git a/src/applications/project/__tests__/PhabricatorProjectCoreTestCase.php b/src/applications/project/__tests__/PhabricatorProjectCoreTestCase.php
index e50c83ab5a..186ac7dea4 100644
--- a/src/applications/project/__tests__/PhabricatorProjectCoreTestCase.php
+++ b/src/applications/project/__tests__/PhabricatorProjectCoreTestCase.php
@@ -1008,29 +1008,32 @@ final class PhabricatorProjectCoreTestCase extends PhabricatorTestCase {
       $task2->getPHID(),
       $task1->getPHID(),
     );
-    $this->assertTasksInColumn($expect, $user, $board, $column);
+    $label = pht('Simple move');
+    $this->assertTasksInColumn($expect, $user, $board, $column, $label);
 
     // Move the second task after the first task.
     $options = array(
-      'afterPHID' => $task1->getPHID(),
+      'afterPHIDs' => array($task1->getPHID()),
     );
     $this->moveToColumn($user, $board, $task2, $column, $column, $options);
     $expect = array(
       $task1->getPHID(),
       $task2->getPHID(),
     );
-    $this->assertTasksInColumn($expect, $user, $board, $column);
+    $label = pht('With afterPHIDs');
+    $this->assertTasksInColumn($expect, $user, $board, $column, $label);
 
     // Move the second task before the first task.
     $options = array(
-      'beforePHID' => $task1->getPHID(),
+      'beforePHIDs' => array($task1->getPHID()),
     );
     $this->moveToColumn($user, $board, $task2, $column, $column, $options);
     $expect = array(
       $task2->getPHID(),
       $task1->getPHID(),
     );
-    $this->assertTasksInColumn($expect, $user, $board, $column);
+    $label = pht('With beforePHIDs');
+    $this->assertTasksInColumn($expect, $user, $board, $column, $label);
   }
 
   public function testMilestoneMoves() {
@@ -1333,7 +1336,8 @@ final class PhabricatorProjectCoreTestCase extends PhabricatorTestCase {
     array $expect,
     PhabricatorUser $viewer,
     PhabricatorProject $board,
-    PhabricatorProjectColumn $column) {
+    PhabricatorProjectColumn $column,
+    $label = null) {
 
     $engine = id(new PhabricatorBoardLayoutEngine())
       ->setViewer($viewer)
@@ -1346,7 +1350,7 @@ final class PhabricatorProjectCoreTestCase extends PhabricatorTestCase {
       $column->getPHID());
     $object_phids = array_values($object_phids);
 
-    $this->assertEqual($expect, $object_phids);
+    $this->assertEqual($expect, $object_phids, $label);
   }
 
   private function addColumn(
diff --git a/src/applications/project/controller/PhabricatorProjectMoveController.php b/src/applications/project/controller/PhabricatorProjectMoveController.php
index 950b1e90cd..273a068c06 100644
--- a/src/applications/project/controller/PhabricatorProjectMoveController.php
+++ b/src/applications/project/controller/PhabricatorProjectMoveController.php
@@ -11,9 +11,20 @@ final class PhabricatorProjectMoveController
 
     $column_phid = $request->getStr('columnPHID');
     $object_phid = $request->getStr('objectPHID');
+
     $after_phid = $request->getStr('afterPHID');
     $before_phid = $request->getStr('beforePHID');
 
+    $after_phids = array();
+    if ($after_phid) {
+      $after_phids[] = $after_phid;
+    }
+
+    $before_phids = array();
+    if ($before_phid) {
+      $before_phids[] = $before_phid;
+    }
+
     $order = $request->getStr('order');
     if (!strlen($order)) {
       $order = PhabricatorProjectColumnNaturalOrder::ORDERKEY;
@@ -89,9 +100,10 @@ final class PhabricatorProjectMoveController
 
     $order_params = array();
     if ($after_phid) {
-      $order_params['afterPHID'] = $after_phid;
-    } else if ($before_phid) {
-      $order_params['beforePHID'] = $before_phid;
+      $order_params['afterPHIDs'] = $after_phids;
+    }
+    if ($before_phid) {
+      $order_params['beforePHIDs'] = $before_phids;
     }
 
     $xactions = array();
diff --git a/src/applications/project/engine/PhabricatorBoardLayoutEngine.php b/src/applications/project/engine/PhabricatorBoardLayoutEngine.php
index dcbe2d4ee4..e614ec2f94 100644
--- a/src/applications/project/engine/PhabricatorBoardLayoutEngine.php
+++ b/src/applications/project/engine/PhabricatorBoardLayoutEngine.php
@@ -135,52 +135,12 @@ final class PhabricatorBoardLayoutEngine extends Phobject {
     return $this;
   }
 
-  public function queueAddPositionBefore(
-    $board_phid,
-    $column_phid,
-    $object_phid,
-    $before_phid) {
-
-    return $this->queueAddPositionRelative(
-      $board_phid,
-      $column_phid,
-      $object_phid,
-      $before_phid,
-      true);
-  }
-
-  public function queueAddPositionAfter(
-    $board_phid,
-    $column_phid,
-    $object_phid,
-    $after_phid) {
-
-    return $this->queueAddPositionRelative(
-      $board_phid,
-      $column_phid,
-      $object_phid,
-      $after_phid,
-      false);
-  }
-
   public function queueAddPosition(
-    $board_phid,
-    $column_phid,
-    $object_phid) {
-    return $this->queueAddPositionRelative(
-      $board_phid,
-      $column_phid,
-      $object_phid,
-      null,
-      true);
-  }
-
-  private function queueAddPositionRelative(
     $board_phid,
     $column_phid,
     $object_phid,
-    $relative_phid,
-    $is_before) {
+    array $after_phids,
+    array $before_phids) {
 
     $board_layout = idx($this->boardLayout, $board_phid, array());
     $positions = idx($board_layout, $column_phid, array());
@@ -196,54 +156,76 @@ final class PhabricatorBoardLayoutEngine extends Phobject {
         ->setObjectPHID($object_phid);
     }
 
-    $found = false;
     if (!$positions) {
       $object_position->setSequence(0);
     } else {
-      foreach ($positions as $position) {
-        if (!$found) {
-          if ($relative_phid === null) {
-            $is_match = true;
-          } else {
-            $position_phid = $position->getObjectPHID();
-            $is_match = ($relative_phid == $position_phid);
+      // The user's view of the board may fall out of date, so they might
+      // try to drop a card under a different card which is no longer where
+      // they thought it was.
+
+      // When this happens, we perform the move anyway, since this is almost
+      // certainly what users want when interacting with the UI. We'l try to
+      // fall back to another nearby card if the client provided us one. If
+      // we don't find any of the cards the client specified in the column,
+      // we'll just move the card to the default position.
+
+      $search_phids = array();
+      foreach ($after_phids as $after_phid) {
+        $search_phids[] = array($after_phid, false);
+      }
+
+      foreach ($before_phids as $before_phid) {
+        $search_phids[] = array($before_phid, true);
+      }
+
+      // This makes us fall back to the default position if we fail every
+      // candidate position. The default position counts as a "before" position
+      // because we want to put the new card at the top of the column.
+      $search_phids[] = array(null, true);
+
+      $found = false;
+      foreach ($search_phids as $search_position) {
+        list($relative_phid, $is_before) = $search_position;
+        foreach ($positions as $position) {
+          if (!$found) {
+            if ($relative_phid === null) {
+              $is_match = true;
+            } else {
+              $position_phid = $position->getObjectPHID();
+              $is_match = ($relative_phid === $position_phid);
+            }
+
+            if ($is_match) {
+              $found = true;
+
+              $sequence = $position->getSequence();
+
+              if (!$is_before) {
+                $sequence++;
+              }
+
+              $object_position->setSequence($sequence++);
+
+              if (!$is_before) {
+                // If we're inserting after this position, continue the loop so
+                // we don't update it.
+                continue;
+              }
+            }
           }
 
-          if ($is_match) {
-            $found = true;
-
-            $sequence = $position->getSequence();
-
-            if (!$is_before) {
-              $sequence++;
-            }
-
-            $object_position->setSequence($sequence++);
-
-            if (!$is_before) {
-              // If we're inserting after this position, continue the loop so
-              // we don't update it.
-              continue;
-            }
+          if ($found) {
+            $position->setSequence($sequence++);
+            $this->addQueue[] = $position;
           }
         }
 
         if ($found) {
-          $position->setSequence($sequence++);
-          $this->addQueue[] = $position;
+          break;
         }
       }
     }
 
-    if ($relative_phid && !$found) {
-      throw new Exception(
-        pht(
-          'Unable to find object "%s" in column "%s" on board "%s".',
-          $relative_phid,
-          $column_phid,
-          $board_phid));
-    }
-
     $this->addQueue[] = $object_position;
 
     $positions[$object_phid] = $object_position;
diff --git a/webroot/rsrc/js/application/projects/WorkboardBoard.js b/webroot/rsrc/js/application/projects/WorkboardBoard.js
index 0cd8abb7d2..7f1383ac64 100644
--- a/webroot/rsrc/js/application/projects/WorkboardBoard.js
+++ b/webroot/rsrc/js/application/projects/WorkboardBoard.js
@@ -495,7 +495,7 @@ JX.install('WorkboardBoard', {
         order: this.getOrder()
       };
 
-      var context = this._getDropContext(after_node);
+      var context = this._getDropContext(after_node, item);
 
       if (context.afterPHID) {
         data.afterPHID = context.afterPHID;