Implemented in 1996, ASOP is based on the containment approach, a nationally recognized, intensive supervision and community-based probation model. The model has three major components: the intensive supervision of offenders, group therapy treatment supplemented with individual counseling, and a partnership between probation officers and treatment providers that includes frequent communication and information-sharing on specific offenders. The research design for the evaluation included a control sample of sex offenders who were convicted of the same crimes as the ASOP sample and were sentenced to standard probation. Data were collected from 208 sex offenders on standard probation in Cook County and compared with data collected on 78 ASOP offenders to determine the impact of the project. Approximately 23 percent of ASOP participants and 18 percent of the control sample offenders were arrested during their probation period. Just over 5 percent of ASOP offenders were arrested for and/or convicted of a sex-related offense, compared with just over 3 percent of control sample offenders. Despite successful implementation and quality treatment, the project was still unable to meet field visit requirements. Evaluation recommendations are to retain home visits as part of the field visits; officers who conduct searches should have detailed knowledge of high-risk behaviors in each case; consideration should be given to assigning all sex offenders to an expanded ASOP unit; and the project should establish uniform criteria for determining treatment progress across agencies. 2 tables