diff --git a/src/wp-includes/default-filters.php b/src/wp-includes/default-filters.php
index 1b1f01c571..70da2f2e2a 100644
--- a/src/wp-includes/default-filters.php
+++ b/src/wp-includes/default-filters.php
@@ -143,6 +143,10 @@ add_filter( 'the_excerpt',     'wpautop'          );
 add_filter( 'the_excerpt',     'shortcode_unautop');
 add_filter( 'get_the_excerpt', 'wp_trim_excerpt'  );
 
+add_filter( 'the_post_thumbnail_caption', 'wptexturize'     );
+add_filter( 'the_post_thumbnail_caption', 'convert_smilies' );
+add_filter( 'the_post_thumbnail_caption', 'convert_chars'   );
+
 add_filter( 'comment_text', 'wptexturize'            );
 add_filter( 'comment_text', 'convert_chars'          );
 add_filter( 'comment_text', 'make_clickable',      9 );
diff --git a/src/wp-includes/post-thumbnail-template.php b/src/wp-includes/post-thumbnail-template.php
index 2b95f4fb70..4722565d96 100644
--- a/src/wp-includes/post-thumbnail-template.php
+++ b/src/wp-includes/post-thumbnail-template.php
@@ -210,3 +210,44 @@ function the_post_thumbnail_url( $size = 'post-thumbnail' ) {
 		echo esc_url( $url );
 	}
 }
+
+/**
+ * Returns the post thumbnail caption.
+ *
+ * @since 4.6.0
+ *
+ * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`.
+ * @return string Post thumbnail caption.
+ */
+function get_the_post_thumbnail_caption( $post = null ) {
+	$post_thumbnail_id = get_post_thumbnail_id( $post );
+	if ( ! $post_thumbnail_id ) {
+		return '';
+	}
+
+	$caption = wp_get_attachment_caption( $post_thumbnail_id );
+
+	if ( ! $caption ) {
+		$caption = '';
+	}
+
+	return $caption;
+}
+
+/**
+ * Displays the post thumbnail caption.
+ *
+ * @since 4.6.0
+ *
+ * @param int|WP_Post $post Optional. Post ID or WP_Post object. Default is global `$post`.
+ */
+function the_post_thumbnail_caption( $post = null ) {
+	/**
+	 * Filters the displayed post thumbnail caption.
+	 *
+	 * @since 4.6.0
+	 *
+	 * @param string $caption Caption for the given attachment.
+	 */
+	echo apply_filters( 'the_post_thumbnail_caption', get_the_post_thumbnail_caption( $post ) );
+}
diff --git a/src/wp-includes/post.php b/src/wp-includes/post.php
index 61f9018cd7..aa15f7239d 100644
--- a/src/wp-includes/post.php
+++ b/src/wp-includes/post.php
@@ -4936,6 +4936,37 @@ function wp_get_attachment_url( $post_id = 0 ) {
 	return $url;
 }
 
+/**
+ * Retrieves the caption for an attachment.
+ *
+ * @since 4.6.0
+ *
+ * @param int $post_id Optional. Attachment ID. Default 0.
+ * @return string|false False on failure. Attachment caption on success.
+ */
+function wp_get_attachment_caption( $post_id = 0 ) {
+	$post_id = (int) $post_id;
+	if ( ! $post = get_post( $post_id ) ) {
+		return false;
+	}
+
+	if ( 'attachment' !== $post->post_type ) {
+		return false;
+	}
+
+	$caption = $post->post_excerpt;
+
+	/**
+	 * Filters the attachment caption.
+	 *
+	 * @since 4.6.0
+	 *
+	 * @param string $caption Caption for the given attachment.
+	 * @param int    $post_id Attachment ID.
+	 */
+	return apply_filters( 'wp_get_attachment_caption', $caption, $post->ID );
+}
+
 /**
  * Retrieve thumbnail for an attachment.
  *
diff --git a/tests/phpunit/tests/media.php b/tests/phpunit/tests/media.php
index 55311a5766..7bd9f49fcf 100644
--- a/tests/phpunit/tests/media.php
+++ b/tests/phpunit/tests/media.php
@@ -901,6 +901,40 @@ EOF;
 		$this->assertEquals( $image[0], wp_get_attachment_image_url( $attachment_id ) );
 	}
 
+	/**
+	 * @ticket 12235
+	 */
+	function test_wp_get_attachment_caption() {
+		$this->assertFalse( wp_get_attachment_caption( 0 ) );
+
+		$caption = 'This is a caption.';
+
+		$post_id = self::factory()->post->create();
+		$attachment_id = self::factory()->attachment->create_object( $this->img_name, $post_id, array(
+			'post_mime_type' => 'image/jpeg',
+			'post_type'      => 'attachment',
+			'post_excerpt'   => $caption,
+		) );
+
+		$this->assertFalse( wp_get_attachment_caption( $post_id ) );
+
+		$this->assertEquals( $caption, wp_get_attachment_caption( $attachment_id ) );
+	}
+
+	/**
+	 * @ticket 12235
+	 */
+	function test_wp_get_attachment_caption_empty() {
+		$post_id = self::factory()->post->create();
+		$attachment_id = self::factory()->attachment->create_object( $this->img_name, $post_id, array(
+			'post_mime_type' => 'image/jpeg',
+			'post_type'      => 'attachment',
+			'post_excerpt'   => '',
+		) );
+
+		$this->assertEquals( '', wp_get_attachment_caption( $attachment_id ) );
+	}
+
 	/**
 	 * Helper function to get image size array from size "name"
 	 */
diff --git a/tests/phpunit/tests/post/thumbnails.php b/tests/phpunit/tests/post/thumbnails.php
index 822154f1ff..ad232c1149 100644
--- a/tests/phpunit/tests/post/thumbnails.php
+++ b/tests/phpunit/tests/post/thumbnails.php
@@ -74,6 +74,63 @@ class Tests_Post_Thumbnail_Template extends WP_UnitTestCase {
 		$this->assertTrue( $WP_Query->thumbnails_cached );
 	}
 
+	/**
+	 * @ticket 12235
+	 */
+	function test_get_the_post_thumbnail_caption() {
+		$this->assertEquals( '', get_the_post_thumbnail_caption() );
+
+		$caption = 'This is a caption.';
+
+		$post_id = self::factory()->post->create();
+		$attachment_id = self::factory()->attachment->create_object( 'image.jpg', $post_id, array(
+			'post_mime_type' => 'image/jpeg',
+			'post_type'      => 'attachment',
+			'post_excerpt'   => $caption,
+		) );
+
+		set_post_thumbnail( $post_id, $attachment_id );
+
+		$this->assertEquals( $caption, get_the_post_thumbnail_caption( $post_id ) );
+	}
+
+	/**
+	 * @ticket 12235
+	 */
+	function test_get_the_post_thumbnail_caption_empty() {
+		$post_id = self::factory()->post->create();
+		$attachment_id = self::factory()->attachment->create_object( 'image.jpg', $post_id, array(
+			'post_mime_type' => 'image/jpeg',
+			'post_type'      => 'attachment',
+			'post_excerpt'   => '',
+		) );
+
+		set_post_thumbnail( $post_id, $attachment_id );
+
+		$this->assertEquals( '', get_the_post_thumbnail_caption( $post_id ) );
+	}
+
+	/**
+	 * @ticket 12235
+	 */
+	function test_the_post_thumbnail_caption() {
+		$caption = 'This is a caption.';
+
+		$post_id = self::factory()->post->create();
+		$attachment_id = self::factory()->attachment->create_object( 'image.jpg', $post_id, array(
+			'post_mime_type' => 'image/jpeg',
+			'post_type'      => 'attachment',
+			'post_excerpt'   => $caption,
+		) );
+
+		set_post_thumbnail( $post_id, $attachment_id );
+
+		ob_start();
+		the_post_thumbnail_caption( $post_id );
+
+		$this->assertEquals( $caption, ob_get_clean() );
+	}
+
 	function test_get_the_post_thumbnail() {
 		$this->assertEquals( '', get_the_post_thumbnail() );
 		$this->assertEquals( '', get_the_post_thumbnail( self::$post ) );