Abstract: An adapter for enabling a traditional cup holder to support a relatively large drinking vessel includes a base having an upwardly opening socket which is large enough to receive the vessel and a downwardly projecting locking element which is small enough to fit into the traditional cup holder. The locking element rotates on the base about an eccentric axis so that when it is turned it will drive the base into a nearby upright surface and thereby hold the base firmly on the traditional cup holder. The base may also be fitted with a hanger for suspending it from the upper edge of a trim panel or some other support.