General Therapeutic Workplace Procedures The study was conducted in a model therapeutic workplace in which employment-based reinforcement contingencies are arranged to promote therapeutic behavior change. All participants were invited to attend the workplace for four hours every weekday to work on training programs that were almost fully automated. Participants earned vouchers that were exchangeable for goods and services in the community. Earnings were based on attendance in the workplace and performance in the training programs. Overall, voucher earnings were arranged such that participants could earn a base pay of $8.00/hour for the hours worked in the workplace plus approximately $2.00/hour for their performance on the training programs, for a total potential wage of $10/hour. Detailed descriptions of the therapeutic workplace, the web-based training programs, the staffing requirements, and the cost of the intervention can be found elsewhere. Participants in the Prescription group were eligible to work and earn vouchers independent of naltrexone consumption and/or drug use, however Contingency participants were only permitted to work when naltrexone consumption was objectively confirmed.