The Beaver County Mentally Ill Substance Abuse (MISA) Treatment Program staff completed core and advanced training in co-occurring disorders; the training curriculum was developed by a statewide committee. Staffing consists of a clinical director, a psychiatrist (16 hours per week), two full-time therapists with experience in mental health and substance abuse treatment, and an administrative assistant. The State requires a staff-to-inmate ratio at or below 1-to-30. The program consists of the primary components of identification, screening and placement, treatment, and transition back into the community. Identification involves targeting the potential MISA-inmate at intake. A correctional counselor interviews an offender, completes a social services assessment, and determines whether the inmate should be referred to a trained MISA evaluator. The MISA evaluator is an experienced therapist who has received specialized training in evaluating individuals for co-occurring mental health and substance-abuse needs. The MISA evaluator determines treatment needs. Based on the evaluation, an inmate may be placed into drug and alcohol programming, mental health programs, or a specialized combination of the two (MISA programming). Once placed into the MISA treatment track, an individual treatment plan is developed by the team, including consultation with the psychiatrist and cooperative participation by the inmate. The primary challenge has been providing aftercare plans for inmates released after short-term treatment. This article describes MISA client characteristics, participation and retention in treatment, and criminal recidivism. 1 figure and 4 notes