Mental health and chemical dependency clinicians have differing beliefs in regard to the etiology, diagnosis, and treatment of dually diagnosed patients. The differing views of the relationship between psychopathology and chemical dependence often result in fragmented and inadequate care, with the patient being shunted back and forth between mental health and chemical dependence treatment facilities. This article includes a discussion of the impediments to effective and comprehensive treatment for dually diagnosed patients as well as a case history to illustrate commonly encotmtered difficulties. A model treatment approach for dually diagnosed patients is described to provide clinical guidelines for effective programing. In addition, a number of recommendations identify needed changes in the mental health and chemical dependency fields at the clinical and administrative levels.