diff --git a/inc/activities/reject.php b/inc/activities/reject.php
new file mode 100644
index 0000000..fecb0c6
--- /dev/null
+++ b/inc/activities/reject.php
@@ -0,0 +1,39 @@
+<?php
+namespace activities\reject;
+
+require_once plugin_dir_path( __FILE__ ) . '/../following.php';
+require_once plugin_dir_path( __FILE__ ) . '/../objects.php';
+require_once plugin_dir_path( __FILE__ ) . '/../actors.php';
+
+function handle_inbox( $actor_slug, $activity ) {
+    if ( !array_key_exists( 'object', $activity ) ) {
+        return new \WP_Error(
+            'invalid_activity',
+            __( 'Activity must have an "object" field', 'pterotype' ),
+            array( 'status' => 400 );
+        );
+    }
+    $object = $activity['object'];
+    if ( array_key_exists( 'type', $object ) ) {
+        switch ( $object['type'] ) {
+        case 'Follow':
+            if ( !array_key_exists( 'object', $object ) ) {
+                break;
+            }
+            $follow_object = $object['object'];
+            if ( !array_key_exists( 'id', $follow_object ) ) {
+                break;
+            }
+            $object_id = \objects\get_object_by_activitypub_id( $follow_object['id'] );
+            if ( is_wp_error( $object_id ) ) {
+                break;
+            }
+            $actor_id = \actors\get_actor_id( $actor_slug );
+            \following\reject_follow( $actor_id, $object_id );
+            break;
+        default:
+            break;
+        }
+    }
+}
+?>
diff --git a/inc/following.php b/inc/following.php
index 7a0a43c..7d8cd9b 100644
--- a/inc/following.php
+++ b/inc/following.php
@@ -27,6 +27,15 @@ function accept_follow( $actor_id, $object_id ) {
     );
 }
 
+function reject_follow( $actor_id, $object_id ) {
+    global $wpdb;
+    return $wpdb->delete(
+        'pterotype_following',
+        array( 'actor_id' => $actor_id, 'object_id' => $object_id ),
+        '%d'
+    );
+}
+
 function get_following_collection( $actor_slug ) {
     global $wpdb;
     $actor_id = \actors\get_actor_id( $actor_slug );
diff --git a/inc/inbox.php b/inc/inbox.php
index 3baff52..5cedbb1 100644
--- a/inc/inbox.php
+++ b/inc/inbox.php
@@ -14,6 +14,8 @@ require_once plugin_dir_path( __FILE__ ) . '/activities/create.php';
 require_once plugin_dir_path( __FILE__ ) . '/activities/update.php';
 require_once plugin_dir_path( __FILE__ ) . '/activities/delete.php';
 require_once plugin_dir_path( __FILE__ ) . '/activities/follow.php';
+require_once plugin_dir_path( __FILE__ ) . '/activities/accept.php';
+require_once plugin_dir_path( __FILE__ ) . '/activities/reject.php';
 
 function handle_activity( $actor_slug, $activity ) {
     if ( !array_key_exists( 'type', $activity ) ) {
@@ -41,14 +43,26 @@ function handle_activity( $actor_slug, $activity ) {
         $activity = \activities\accept\handle_inbox( $actor_slug, $activity );
         break;
     case 'Reject':
+        $activity = \activities\reject\handle_inbox( $actor_slug, $activity );
         break;
     case 'Add':
+        return new \WP_Error(
+            'not_implemented',
+            __( 'The Add activity has not been implemented', 'pterotype' ),
+            array( 'status' => 501 )
+        );
         break;
     case 'Remove':
+        return new \WP_Error(
+            'not_implemented',
+            __( 'The Remove activity has not been implemented', 'pterotype' ),
+            array( 'status' => 501 )
+        );
         break;
     case 'Announce':
         break;
     case 'Undo':
+        // TODO
         break;
     }
     if ( is_wp_error( $activity ) ) {