Resident compatibility and staff preparedness are major determinants of the success or failure of residential combined treatment programs. At Eagleville Hospital, the extent to which alcoholics, addicts, and multiple substance abusers are similar/different with respect to personality needs, self-concept, psychopathology, and self-reported problems has been the subject for study for nearly a decade. Research findings consistently show greater similarities than differences, when appropriate statistical controls are exercised for demographic variables (e.g., age, race, and sex). Conscious, overt combined treatment programs require building consensual support among staff for such treatment, providing generic education and training, and recruiting appropriate role models of recovery. Programmaric considerations recognizing the diversity of patient life-styles likely to be found in a residential combined treatment program are enumerated.