This longitudinal outcomes research study described substance abuse treatment services for drug court participants and comparison group offenders in Oregon (which has one of the country’s oldest drug court programs). This project examined cohorts of offenders prior to and after Medicaid managed care (the Oregon Health Plan) had been implemented. Drug court participants were compared with similar offenders who were eligible for but did not participate in drug court. Medicaid clients were compared with non-Medicaid clients. Process measures included the modality and extent of drug abuse treatment services.