The program operated in two units (Prep and Shock Units), each of which housed 40 men and had a military-style setting. Inmates spent 4-8 weeks in the Prep Unit and then moved to the Shock Unit, where they completed a 3-month, 36-sessin rotation of the Residential Substance Abuse Treatment (RSAT) Group. Inmates had a total of 6 months of drug treatment. The program blended 12-step programming with cognitive-behavioral therapy and social skills training. The evaluation took place during March-December 1999. Information came from program records, a review of the program curriculum and other materials, interviews with relevant staff and an outside vendor, focus groups with inmates, and informal observations of the program. Results revealed that 26 percent of the 309 entries into the program during the 1-year evaluation period resulted in graduation, 41 percent were terminated by staff, 29 percent were released early, 2 percent dropped out, and 2 percent were still in the program at the time of analysis. The program has successfully incorporated 13 of the 18 recognized principles of effective drug treatment programs and has partially achieved the remaining 5 principles. Recommended actions to improve the program’s operation include increasing human services and custody staff by one full-time position each, continuing or initiating training for all staff in cognitive-behavioral therapy, better informing inmates about the program before they enter it, and establishing written classification eligibility criteria for inmates moving into the Shock unit. Additional recommendations, tables, figures, appended background on the management information system, and 44 references