In 1993, the Therapeutic Community (TC) within the Colorado Department of Corrections was created. TC is based on the sex offender and substance abuse literature as a promising method of creating lasting change among its residents. In 2000, the State of Colorado had identified approximately 24 percent of its adult incarcerated population as sex offenders. With support from the U.S. Department of Justice, Office of Justice Programs, the Colorado Division of Criminal Justice, Office of Research and Statistics conducted an evaluation of the therapeutic community, specifically the Sex Offender Treatment and Monitoring Program (SOTMP) under the Colorado Department of Corrections. This report presents the results of this evaluation, which examines whether the fundamental components of the TC are firmly grounded in theory and best practices, and if sex offenders who receive TC services are less likely to be rearrested than sex offenders who do not receive services. Findings are presented for both program integrity which include the components of theoretical and philosophical basis, clinical principles, administration, staffing, facility/environment, TC program element, TC process, stages of treatment, community TC and clinical management, intake screening and assessment, and community-based aftercare and outcome findings/recidivism. The report findings reflect the challenges of service delivery in a correctional environment. The SOTMP offers a comprehensive, intense program for Phase 1 offenders: a minimum of 6 months of psycho-educational group sessions with meetings four times a week. Only those who complete Phase 1 are considered for placement in the TC offering a living/working environment focused on treatment. The minimum length of stay is 1 year in the TC. The resources devoted to this effort, combined with the offenders’ efforts to change, appear to profoundly improve public safety as measured by officially recorded recidivism. Tables, figures, references and appendixes A-R