diff --git a/src/applications/calendar/application/PhabricatorCalendarApplication.php b/src/applications/calendar/application/PhabricatorCalendarApplication.php
--- a/src/applications/calendar/application/PhabricatorCalendarApplication.php
+++ b/src/applications/calendar/application/PhabricatorCalendarApplication.php
@@ -53,7 +53,7 @@
             => 'PhabricatorCalendarEventEditController',
           'cancel/(?P<id>[1-9]\d*)/'
             => 'PhabricatorCalendarEventCancelController',
-          'join/(?P<id>[1-9]\d*)/'
+          '(?P<action>join|decline|accept)/(?P<id>[1-9]\d*)/'
             => 'PhabricatorCalendarEventJoinController',
         ),
       ),
diff --git a/src/applications/calendar/controller/PhabricatorCalendarEventEditController.php b/src/applications/calendar/controller/PhabricatorCalendarEventEditController.php
--- a/src/applications/calendar/controller/PhabricatorCalendarEventEditController.php
+++ b/src/applications/calendar/controller/PhabricatorCalendarEventEditController.php
@@ -65,6 +65,7 @@
 
       $subscribers = PhabricatorSubscribersQuery::loadSubscribersForPHID(
         $event->getPHID());
+
       $invitees = array();
       foreach ($event->getInvitees() as $invitee) {
         if ($invitee->isUninvited()) {
@@ -84,12 +85,12 @@
       $end_value = $end_time->readValueFromRequest($request);
       $description = $request->getStr('description');
       $subscribers = $request->getArr('subscribers');
+
       $invitees = $request->getArr('invitees');
       $new_invitees = $this->getNewInviteeList($invitees, $event);
-
+      $status_attending = PhabricatorCalendarEventInvitee::STATUS_ATTENDING;
       if ($this->isCreate()) {
         $status = idx($new_invitees, $user->getPHID());
-        $status_attending = PhabricatorCalendarEventInvitee::STATUS_ATTENDING;
         if ($status) {
           $new_invitees[$user->getPHID()] = $status_attending;
         }
@@ -256,13 +257,8 @@
 
     $new = array();
     foreach ($phids as $phid) {
-      $old_invitee = idx($invitees, $phid);
-      if ($old_invitee) {
-        $old_status = $old_invitee->getStatus();
-        if ($old_status != $uninvited_status) {
-          continue;
-        }
-      }
+      $old_status = $event->getUserInviteStatus($phid);
+      if ($old_status != $uninvited_status) { continue; }
       $new[$phid] = $invited_status;
     }
 
diff --git a/src/applications/calendar/controller/PhabricatorCalendarEventJoinController.php b/src/applications/calendar/controller/PhabricatorCalendarEventJoinController.php
--- a/src/applications/calendar/controller/PhabricatorCalendarEventJoinController.php
+++ b/src/applications/calendar/controller/PhabricatorCalendarEventJoinController.php
@@ -5,8 +5,14 @@
 
   private $id;
 
+  const ACTION_ACCEPT = 'accept';
+  const ACTION_DECLINE = 'decline';
+  const ACTION_JOIN = 'join';
+
   public function handleRequest(AphrontRequest $request) {
     $this->id = $request->getURIData('id');
+    $action = $request->getURIData('action');
+
     $request = $this->getRequest();
     $viewer = $request->getViewer();
     $declined_status = PhabricatorCalendarEventInvitee::STATUS_DECLINED;
@@ -54,7 +60,8 @@
       }
     }
 
-    if (!$is_attending) {
+    if (($action == self::ACTION_JOIN && !$is_attending)
+      || $action == self::ACTION_ACCEPT) {
       $title = pht('Join Event');
       $paragraph = pht('Would you like to join this event?');
       $submit = pht('Join');
diff --git a/src/applications/calendar/controller/PhabricatorCalendarEventViewController.php b/src/applications/calendar/controller/PhabricatorCalendarEventViewController.php
--- a/src/applications/calendar/controller/PhabricatorCalendarEventViewController.php
+++ b/src/applications/calendar/controller/PhabricatorCalendarEventViewController.php
@@ -56,16 +56,44 @@
 
   private function buildHeaderView(PhabricatorCalendarEvent $event) {
     $viewer = $this->getRequest()->getUser();
+    $id = $event->getID();
+
     $is_cancelled = $event->getIsCancelled();
     $icon = $is_cancelled ? ('fa-times') : ('fa-calendar');
     $color = $is_cancelled ? ('grey') : ('green');
     $status = $is_cancelled ? ('Cancelled') : ('Active');
 
-    return id(new PHUIHeaderView())
+    $invite_status = $event->getUserInviteStatus($viewer->getPHID());
+    $status_invited = PhabricatorCalendarEventInvitee::STATUS_INVITED;
+    $is_invite_pending = ($invite_status == $status_invited);
+
+    $header = id(new PHUIHeaderView())
       ->setUser($viewer)
       ->setHeader($event->getName())
       ->setStatus($icon, $color, $status)
       ->setPolicyObject($event);
+
+    if ($is_invite_pending) {
+      $decline_button = id(new PHUIButtonView())
+        ->setTag('a')
+        ->setIcon(id(new PHUIIconView())
+          ->setIconFont('fa-times grey'))
+        ->setHref($this->getApplicationURI("/event/decline/{$id}/"))
+        ->setWorkflow(true)
+        ->setText(pht('Decline'));
+
+      $accept_button = id(new PHUIButtonView())
+        ->setTag('a')
+        ->setIcon(id(new PHUIIconView())
+          ->setIconFont('fa-check green'))
+        ->setHref($this->getApplicationURI("/event/accept/{$id}/"))
+        ->setWorkflow(true)
+        ->setText(pht('Accept'));
+
+      $header->addActionLink($decline_button)
+        ->addActionLink($accept_button);
+    }
+    return $header;
   }
 
   private function buildActionView(PhabricatorCalendarEvent $event) {
@@ -153,8 +181,8 @@
       $item = new PHUIStatusItemView();
       $invitee_phid = $invitee->getInviteePHID();
       $target = $viewer->renderHandle($invitee_phid);
-      $item->setNote($invitee->getStatus());
-      $item->setTarget($target);
+      $item->setNote($invitee->getStatus())
+        ->setTarget($target);
       $invitee_list->addItem($item);
     }