The Federal Bureau of Prisons undertook an evaluation of its residential drug abuse treatment program by assessing the post-release outcomes of inmates released from Bureau of Prisons custody. We reprint the Executive Summary of the BOP report, which found that offenders who completed the residential drug abuse treatment program and had been released to the community for three years were significantly less likely to be re-arrested or to be detected for drug use than were similar inmates who did not participate in the program.