From 2003 to 2008, Treatment Alternatives for Safe Communities of Illinois (TASC) implemented the Reducing Risk: Outreach and Pretreatment for Probationers program (RROPP) in Cook County (Chicago), Illinois. The goal of RROPP was to reduce probationers' further penetration into the criminal justice system by increasing participation in substance abuse treatment. To achieve this goal, TASC incorporated evidence-based practices for enhancing the effectiveness of pretreatment services. An outcome evaluation assessed the extent to which RROPP's proposed goals were achieved. The evaluation also obtained useful information regarding lessons learned in the implementation of pretreatment services for probationers. Participation in TRGs was related positively to treatment entry, length of stay in first treatment episode, and completion of first treatment episode. (Contains 3 tables.)