Discusses the rationale for and importance of a multicultural approach to providing mental health services to immigrants and refugees as well as to undocumented aliens and guest workers. Such an approach would encompass both the specific needs of newcomers and their overall adjustment to a new environment. While cultural differences between dominant and non-dominant groups often are evident, within-group ethnic differences are easily overlooked, thus hindering successful implementation of multiculturally oriented mental health services. The Diagnostic and Statistical Manual IV (DSM-IV) may not be sufficient to obtain accurate client assessments of clinical and personality disorders, medical condition, psychological and environmental problems, and overall functioning. The timing may be right to augment this behavioral measure with a three-dimensional cultural model. This cultural model, or interface, views behavior as the result of the ongoing interplay between biology, individual thoughts and feelings, and the larger society. Multiculturally sensitive mental health services can be effective if they are based on the notion of a three-dimensional cultural interface and if mental health providers are both open to new concepts and willing to respect and acknowledge cultures that are strange to them.