Describes a dual diagnosis program that exists in the California Department of Corrections. Program residents must meet the diagnostic criteria of having a major mental disorder and also meet the criteria for a substance abuse/dependence disorder. All patients are housed in one wing of the facility, which is based on the format of a modified therapeutic community and focuses on the concept of recovery. A multidisciplinary treatment team comprised of a psychiatrist, a psychologist, a social worker and a psychiatric technician delivers clinical interventions, including individual and group therapy, and medication management. The focus of the drug treatment aspect is an Alcoholics Anonymous/Narcotics Anonymous approach based on 12-Step philosophy. Research involving other therapeutic communities running in prisons is discussed as is the aspect of dual diagnosis programs. A summary section reflects on aspects that have been successful, what has not worked or has been changed, and upcoming program revisions. (PsycINFO Database Record (c) 2019 APA, all rights reserved)