This study evaluated treatment outcomes for the reduction of criminal justice involvement and substance use among opioid dependent clients in a therapeutic community setting under California's Proposition 36. We compared treatment outcomes between those mandated to treatment under Proposition 36 (n = 24) and those on probation but not involved in Proposition 36 (n = 61) over 12 months. Over time, both groups showed significant improvement on drug use and employment measures, were more likely to be involved in job training and less likely to be engaged in work activity, and had similar retention in treatment. There was no evidence that treatment outcomes were different between the two groups. These findings may be helpful in guiding policy makers and clinicians in states where similar initiatives are under consideration.