This Research for Practice examines the Residential Substance Abuse Treatment (RSAT) program at the South Idaho Correctional Institution. The program targets parole-violating inmates with substance abuse problems in an effort to reduce recidivism. Researchers conducted a 15-month evaluation of the program's process to identify strengths and weaknesses. Evaluators found Idaho's RSAT program succeeds in part because it combines the most successful known substance abuse treatment approaches used in correctional facilities: a strict process for screening potential participants; the establishment of a therapeutic community; a combination of treatment types--cognitive self-change and behavioral strategies and a 12-step program; the intense involvement of inmates in their own problem solving and development; and an emphasis on the need for a structured aftercare component. Evaluators observed that program participants seemed to have developed prosocial attitudes after participation in the program, and they speculated that the program would likely reduce incarceration costs. These findings may be instructional for other correctional facilities grappling with similar problems. (GCP)