Because of immigration in the West, increased cultural diversity poses a variety of problems for the criminal justice system. This paper examines whether a so-called “cultural defense” ought to be allowed as a freestanding defense to a criminal charge. Such a defense would “negate or mitigate criminal responsibility where acts are committed under a reasonable good-faith belief in their propriety, based on the actor's cultural heritage or tradition.” The cultural defense, as a formal defense, and the use of cultural evidence in order to buttress one of the traditional defenses, are distinguished. Three cases are discussed to illustrate the issues. The possible similarity of the cultural defense to an ignorance or mistake of law defense is then considered. The latter is accepted by such theorists as Gunther Arzt and George P. Fletcher and also apparently in German law, but it is rejected by Jerome Hall on the ground that it undermines the objectivity of the criminal law. The similarity, however, is shown not to hold. It is concluded that a freestanding cultural defense should not be allowed.