diff --git a/inc/network/includes-network.php b/inc/network/includes-network.php
index fefa86b..a38957e 100644
--- a/inc/network/includes-network.php
+++ b/inc/network/includes-network.php
@@ -99,6 +99,22 @@ function get_clean_basedomain() {
 	return $domain;
 }
 
+/**
+ * Returns the warning message about subdirectory multisites not liking custom wp-content directories.
+ *
+ * Applies the 'pantheon.subdirectory_networks_message' filter.
+ *
+ * @since 1.4.5
+ * @return string Warning message or empty string.
+ */
+function pantheon_get_subdirectory_networks_message() {
+	if ( apply_filters( 'pantheon.enable_subdirectory_networks_message', true ) ) {
+		return '<div class="error inline"><p><strong>' . __( 'Warning:' ) . '</strong> ' . __( 'Subdirectory networks may not be fully compatible with custom wp-content directories.' ) . '</p></div>';
+	}
+
+	return '';
+}
+
 /**
  * Prints step 1 for Network installation process.
  *
@@ -231,7 +247,7 @@ function network_step1( $errors = false ) {
 	endif;
 
 	if ( WP_CONTENT_DIR !== ABSPATH . 'wp-content' && ( allow_subdirectory_install() || ! allow_subdomain_install() ) ) {
-		echo '<div class="error inline"><p><strong>' . esc_html__( 'Warning:' ) . '</strong> ' . esc_html__( 'Subdirectory networks may not be fully compatible with custom wp-content directories.' ) . '</p></div>';
+		echo esc_html( pantheon_get_subdirectory_networks_message() );
 	}
 
 	$is_www = ( 0 === strpos( $hostname, 'www.' ) );
@@ -595,7 +611,8 @@ function network_step2( $errors = false ) {
 			);
 		echo '</p>';
 		if ( ! $subdomain_install && WP_CONTENT_DIR !== ABSPATH . 'wp-content' ) {
-			echo '<p><strong>' . esc_html__( 'Warning:' ) . ' ' . esc_html__( 'Subdirectory networks may not be fully compatible with custom wp-content directories.' ) . '</strong></p>';
+			// Display the subdirectory networks message unless filtered.
+			echo esc_html( pantheon_get_subdirectory_networks_message() );
 		}
 		?>
 			<p class="configuration-rules-label"><label for="network-webconfig-rules">
@@ -657,7 +674,8 @@ function network_step2( $errors = false ) {
 		);
 		echo '</p>';
 		if ( ! $subdomain_install && WP_CONTENT_DIR !== ABSPATH . 'wp-content' ) {
-			echo '<p><strong>' . esc_html__( 'Warning:' ) . ' ' . esc_html__( 'Subdirectory networks may not be fully compatible with custom wp-content directories.' ) . '</strong></p>';
+			// Display the subdirectory networks message unless filtered.
+			echo esc_html( pantheon_get_subdirectory_networks_message() );
 		}
 		?>
 			<p class="configuration-rules-label"><label for="network-htaccess-rules">
diff --git a/tests/phpunit/test-network.php b/tests/phpunit/test-network.php
index b7b05f4..e91cad3 100644
--- a/tests/phpunit/test-network.php
+++ b/tests/phpunit/test-network.php
@@ -73,4 +73,14 @@ public function test_get_clean_basedomain() {
 	public function test_pantheon_remove_network_setup() {
 		$this->assertNull( Pantheon\NetworkSetup\pantheon_remove_network_setup() );
 	}
+
+	public function test_disable_subdirectory_custom_wp_content_warning() {
+		// Test the default condition.
+		$this->assertNotEmpty( pantheon_get_subdirectory_networks_message() );
+	}
+
+	public function test_disable_subdirectory_custom_wp_content_warning_filtered() {
+		add_filter( 'pantheon.enable_subdirectory_networks_message', '__return_false' );
+		$this->assertEmpty( pantheon_get_subdirectory_networks_message() );
+	}
 }