diff --git a/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php b/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
index ec1588b02f..a29f92c56f 100644
--- a/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
+++ b/wp-includes/rest-api/endpoints/class-wp-rest-posts-controller.php
@@ -1998,6 +1998,10 @@ class WP_REST_Posts_Controller extends WP_REST_Controller {
 					$data['generated_slug'] = $sample_permalink[1];
 				}
 			}
+
+			if ( rest_is_field_included( 'class_list', $fields ) ) {
+				$data['class_list'] = get_post_class( array(), $post->ID );
+			}
 		}
 
 		$context = ! empty( $request['context'] ) ? $request['context'] : 'view';
@@ -2353,6 +2357,16 @@ class WP_REST_Posts_Controller extends WP_REST_Controller {
 				'context'     => array( 'edit' ),
 				'readonly'    => true,
 			);
+
+			$schema['properties']['class_list'] = array(
+				'description' => __( 'An array of the class names for the post container element.' ),
+				'type'        => 'array',
+				'context'     => array( 'view', 'edit' ),
+				'readonly'    => true,
+				'items'       => array(
+					'type' => 'string',
+				),
+			);
 		}
 
 		if ( $post_type_obj->hierarchical ) {
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 6599f6a9bc..967df0cbe5 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.6-alpha-58325';
+$wp_version = '6.6-alpha-58326';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.