diff --git a/wp-includes/blocks/index.php b/wp-includes/blocks/index.php
index 23cbc78d26..8b0ab4652b 100644
--- a/wp-includes/blocks/index.php
+++ b/wp-includes/blocks/index.php
@@ -44,7 +44,7 @@ function register_core_block_style_handles() {
 	 * Ignore transient cache when the development mode is set to 'core'. Why? To avoid interfering with
 	 * the core developer's workflow.
 	 */
-	if ( 'core' !== wp_get_development_mode() ) {
+	if ( ! wp_in_development_mode( 'core' ) ) {
 		$transient_name = 'wp_core_block_css_files';
 		$files          = get_transient( $transient_name );
 		if ( ! $files ) {
diff --git a/wp-includes/default-constants.php b/wp-includes/default-constants.php
index 294cdc40e5..d28b9fd10b 100644
--- a/wp-includes/default-constants.php
+++ b/wp-includes/default-constants.php
@@ -79,8 +79,8 @@ function wp_initial_constants() {
 
 	/*
 	 * Add define( 'WP_DEVELOPMENT_MODE', 'core' ) or define( 'WP_DEVELOPMENT_MODE', 'plugin' ) or
-	 * define( 'WP_DEVELOPMENT_MODE', 'theme' ) to wp-config.php to signify development mode for WordPress core, a
-	 * plugin, or a theme respectively.
+	 * define( 'WP_DEVELOPMENT_MODE', 'theme' ) or define( 'WP_DEVELOPMENT_MODE', 'all' ) to wp-config.php
+	 * to signify development mode for WordPress core, a plugin, a theme, or all three types respectively.
 	 */
 	if ( ! defined( 'WP_DEVELOPMENT_MODE' ) ) {
 		define( 'WP_DEVELOPMENT_MODE', '' );
diff --git a/wp-includes/deprecated.php b/wp-includes/deprecated.php
index 74fdfb7887..812bf54f23 100644
--- a/wp-includes/deprecated.php
+++ b/wp-includes/deprecated.php
@@ -5233,7 +5233,7 @@ function wp_get_global_styles_svg_filters() {
 	 * Ignore cache when the development mode is set to 'theme', so it doesn't interfere with the theme
 	 * developer's workflow.
 	 */
-	$can_use_cached = wp_get_development_mode() !== 'theme';
+	$can_use_cached = ! wp_in_development_mode( 'theme' );
 	$cache_group    = 'theme_json';
 	$cache_key      = 'wp_get_global_styles_svg_filters';
 	if ( $can_use_cached ) {
diff --git a/wp-includes/global-styles-and-settings.php b/wp-includes/global-styles-and-settings.php
index d674434313..4b21ce6cf0 100644
--- a/wp-includes/global-styles-and-settings.php
+++ b/wp-includes/global-styles-and-settings.php
@@ -69,7 +69,7 @@ function wp_get_global_settings( $path = array(), $context = array() ) {
 	 * Ignore cache when the development mode is set to 'theme', so it doesn't interfere with the theme
 	 * developer's workflow.
 	 */
-	$can_use_cached = wp_get_development_mode() !== 'theme';
+	$can_use_cached = ! wp_in_development_mode( 'theme' );
 
 	$settings = false;
 	if ( $can_use_cached ) {
@@ -152,7 +152,7 @@ function wp_get_global_stylesheet( $types = array() ) {
 	 * Ignore cache when the development mode is set to 'theme', so it doesn't interfere with the theme
 	 * developer's workflow.
 	 */
-	$can_use_cached = empty( $types ) && wp_get_development_mode() !== 'theme';
+	$can_use_cached = empty( $types ) && ! wp_in_development_mode( 'theme' );
 
 	/*
 	 * By using the 'theme_json' group, this data is marked to be non-persistent across requests.
@@ -251,7 +251,7 @@ function wp_get_global_styles_custom_css() {
 	 * Ignore cache when the development mode is set to 'theme', so it doesn't interfere with the theme
 	 * developer's workflow.
 	 */
-	$can_use_cached = wp_get_development_mode() !== 'theme';
+	$can_use_cached = ! wp_in_development_mode( 'theme' );
 
 	/*
 	 * By using the 'theme_json' group, this data is marked to be non-persistent across requests.
@@ -360,7 +360,7 @@ function wp_theme_has_theme_json() {
 		 * Ignore static cache when the development mode is set to 'theme', to avoid interfering with
 		 * the theme developer's workflow.
 		 */
-		wp_get_development_mode() !== 'theme'
+		! wp_in_development_mode( 'theme' )
 	) {
 		return $theme_has_support[ $stylesheet ];
 	}
diff --git a/wp-includes/load.php b/wp-includes/load.php
index ab2a91cd78..36e8a5aa6f 100644
--- a/wp-includes/load.php
+++ b/wp-includes/load.php
@@ -271,11 +271,15 @@ function wp_get_environment_type() {
  * The development mode affects how certain parts of the WordPress application behave, which is relevant when
  * developing for WordPress.
  *
- * Valid developer modes are 'core', 'plugin', 'theme', or an empty string to disable developer mode.
+ * Valid development modes are 'core', 'plugin', 'theme', 'all', or an empty string to disable development mode.
+ * 'all' is a special value to signify that all three development modes 'core', 'plugin', and 'theme' are enabled.
  *
  * Developer mode is considered separately from `WP_DEBUG` and {@see wp_get_environment_type()}. It does not affect
  * debugging output, but rather functional nuances in WordPress.
  *
+ * This function controls the currently set development mode value. To check for whether a specific development mode is
+ * enabled, use wp_in_development_mode().
+ *
  * @since 6.3.0
  *
  * @return string The current development mode.
@@ -298,6 +302,7 @@ function wp_get_development_mode() {
 		'core',
 		'plugin',
 		'theme',
+		'all',
 		'',
 	);
 	if ( ! in_array( $development_mode, $valid_modes, true ) ) {
@@ -309,6 +314,29 @@ function wp_get_development_mode() {
 	return $current_mode;
 }
 
+/**
+ * Checks whether the site is in the given development mode.
+ *
+ * @since 6.3.0
+ *
+ * @param string $mode Development mode to check for. Either 'core', 'plugin', 'theme', or 'all'.
+ * @return bool True if the given mode is covered by the current development mode, false otherwise.
+ */
+function wp_in_development_mode( $mode ) {
+	$current_mode = wp_get_development_mode();
+	if ( empty( $current_mode ) ) {
+		return false;
+	}
+
+	// Return true if the current mode encompasses all modes.
+	if ( 'all' === $current_mode ) {
+		return true;
+	}
+
+	// Return true if the current mode is the given mode.
+	return $mode === $current_mode;
+}
+
 /**
  * Ensures all of WordPress is not loaded when handling a favicon.ico request.
  *
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 2a5e048679..322b49a97c 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.3-beta4-56222';
+$wp_version = '6.3-beta4-56223';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.