The potential application of behaviour therapy to cross-cultural situations is explored as societies move to recognise their bicultural or multicultural composition. First reviewed are the moral and epistemological underpinnings of behaviour therapy and questions involving the universality of behaviour principles and technologies. Expected competencies of cross-cultural therapists are next raised. The basic message, told through examples from Australia, North American, and elsewhere, is that cultural norms and values penetrate every facet of client–therapist interaction and clinical decision-making. Competently performed functional analyses can produce culturally accommodating interventions that respond to culture-specific definitions of deviancy, accepted norms of role behaviour, expectations of change techniques, and approved behaviour change practitioners.