In past years significant advances have been made in both the conceptualization and development of innovative program models providing integrated assessment and concommitant treatment for dually disordered patients. The purpose of this volume is to provide the reader with information about the most current ideas and clinical interventions available. Although many of the models presented here have been successful only in clinical trials, and efficacy is not yet confirmed by controlled research, the principles used in the development of these models hopefully will have value in assisting clinicians, managers, and planners who have an immediate need to provide services to this population. This is the 50th issue of the quarterly journal New Directions for Mental Health Services.