diff --git a/inc/activities.php b/inc/activities.php
index 108e358..f43f6ad 100644
--- a/inc/activities.php
+++ b/inc/activities.php
@@ -29,6 +29,13 @@ function get_activity_by_activitypub_id( $activitypub_id ) {
     return $activity;
 }
 
+function get_activity_id( $activitypub_id ) {
+    global $wpdb;
+    return $wpdb->get_var( $wpdb->prepare(
+        'SELECT id FROM pterotype_activities WHERE activitypub_id = %s', $activitypub_id
+    ) );
+}
+
 function strip_private_fields( $activity ) {
     if ( array_key_exists( 'bto', $activity ) ) {
         unset( $activity['bto'] );
diff --git a/inc/activities/announce.php b/inc/activities/announce.php
new file mode 100644
index 0000000..07d59b2
--- /dev/null
+++ b/inc/activities/announce.php
@@ -0,0 +1,45 @@
+<?php
+namespace activities\announce;
+
+require_once plugin_dir_path( __FILE__ ) . '/../objects.php';
+require_once plugin_dir_path( __FILE__ ) . '/../shares.php';
+
+function handle_inbox( $actor_slug, $activity ) {
+    if ( !array_key_exists( 'object', $activity ) ) {
+        return new \WP_Error(
+            'invalid_activity',
+            __( 'Expected an "object" field', 'pterotype' ),
+            array( 'status' => 400 )
+        );
+    }
+    $object = $activity['object'];
+    if ( !array_key_exists( 'id', $object ) ) {
+        return new \WP_Error(
+            'invalid_activity',
+            __( 'Expected an "id" field', 'pterotype' ),
+            array( 'status' => 400 )
+        );
+    }
+    if ( !\objects\is_local_object( $object ) ) {
+        return $activity;
+    }
+    $object_id = \objects\get_object_id( $object['id'] );
+    if ( !$object_id ) {
+        return new \WP_Error(
+            'not_found',
+            __( 'Object not found', 'pterotype' ),
+            array( 'status' => 404 )
+        );
+    }
+    $activity_id = \activities\get_activity_id( $activity['id'] );
+    if ( !$activity_id ) {
+        return new \WP_Error(
+            'not_found',
+            __( 'Activity not found', 'pterotype' ),
+            array( 'status' => 404 )
+        );
+    }
+    \shares\add_share( $object_id, $activity_id );
+    return $activity;
+}
+?>
diff --git a/inc/inbox.php b/inc/inbox.php
index 5cedbb1..ab09937 100644
--- a/inc/inbox.php
+++ b/inc/inbox.php
@@ -16,6 +16,7 @@ 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';
+require_once plugin_dir_path( __FILE__ ) . '/activities/announce.php';
 
 function handle_activity( $actor_slug, $activity ) {
     if ( !array_key_exists( 'type', $activity ) ) {
@@ -26,6 +27,10 @@ function handle_activity( $actor_slug, $activity ) {
         );
     }
     forward_activity( $activity );
+    $res = persist_activity( $actor_slug, $activity );
+    if ( is_wp_error( $res ) ) {
+        return $res;
+    }
     switch ( $activity['type'] ) {
     case 'Create':
         $activity = \activities\create\handle_inbox( $actor_slug, $activity );
@@ -60,6 +65,7 @@ function handle_activity( $actor_slug, $activity ) {
         );
         break;
     case 'Announce':
+        $activity = \activities\announce\handle_inbox( $actor_slug, $activity );
         break;
     case 'Undo':
         // TODO
@@ -68,7 +74,7 @@ function handle_activity( $actor_slug, $activity ) {
     if ( is_wp_error( $activity ) ) {
         return $activity;
     }
-    return persist_activity( $actor_slug, $activity );
+    return $res;
 }
 
 function forward_activity( $activity ) {
diff --git a/inc/likes.php b/inc/likes.php
index 92358d1..607f7d0 100644
--- a/inc/likes.php
+++ b/inc/likes.php
@@ -1,6 +1,9 @@
 <?php
 namespace likes;
 
+// TODO implement a 'likes' collection for objects -
+// implemented similar to/same as 'shares' collection
+
 function create_like( $actor_id, $object_id ) {
     global $wpdb;
     return $wpdb->insert(
diff --git a/inc/migrations.php b/inc/migrations.php
index 924c6b5..5430d89 100644
--- a/inc/migrations.php
+++ b/inc/migrations.php
@@ -177,5 +177,19 @@ function migration_0_0_3() {
         ENGINE=InnoDB DEFAULT CHARSET=utf8;
        "
     );
+    $wpdb->query(
+        "
+       CREATE TABLE pterotype_shares(
+           object_id INT UNSIGNED NOT NULL,
+           announce_id INT UNSIGNED NOT NULL,
+           PRIMARY KEY (object_id, shared_by),
+           FOREIGN KEY shares_object_fk(object_id)
+               REFERENCES pterotype_objects(id),
+           FOREIGN KEY shares_activity_fk(object_id)
+               REFERENCES pterotype_activities(id)
+       )
+       ENGINE=InnoDB DEFAULT CHARSET=utf8;
+       "
+    );
 }
 ?>
diff --git a/inc/objects.php b/inc/objects.php
index aae7f19..7126ec2 100644
--- a/inc/objects.php
+++ b/inc/objects.php
@@ -232,4 +232,15 @@ function make_tombstone( $object ) {
     );
     return $tombstone;
 }
+
+function is_local_object( $object ) {
+    if ( array_key_exists( 'id', $object ) ) {
+        $parsed = parse_url( $object['id'] );
+        if ( $parsed ) {
+            $site_host = parse_url( get_site_url() )['host'];
+            return $parsed['host'] === $site_host;
+        }
+    }
+    return false;
+}
 ?>
diff --git a/inc/shares.php b/inc/shares.php
new file mode 100644
index 0000000..fce2530
--- /dev/null
+++ b/inc/shares.php
@@ -0,0 +1,15 @@
+<?php
+namespace shares;
+
+function add_share( $object_id, $activity_id ) {
+    global $wpdb;
+    return $wpdb->insert(
+        'pterotype_shares',
+        array(
+            'object_id' => $object_id,
+            'activity_id' => $activity_id,
+        ),
+        '%d'
+    );
+}
+?>