The purpose of this study is to evaluate the effectiveness of a low-cost contingency management procedure as compared to standard treatment. Using a cross-over design, CM is implemented at different community-based clinics and compared with non-CM in the same facilities. Research staff collects information regarding patients' demographic characteristics, attendance, and outcomes at the clinics. During Phase A (non-CM), standard clinical practice is in place. During Phase B (CM), all patients have the chance to win prizes by coming to treatment. Each participating clinic is randomly assigned to receive either the A or B phase first; each phase is in effect for 16 weeks.

Subjects will be patients in treatment at one of the participating clinics during the study period. There are no other inclusion or exclusion criteria because we wish to make enrollment open to increase generalizability.