Contingency management for people with AOD use disorders involves rewarding or reinforcing desired behaviour in the client in a supportive manner [411]. Examples are vouchers for negative urine samples, for treatment attendance, or for medication compliance. There is evidence that contingency management techniques can be used successfully to treat problematic AOD use [412-417]. Studies have also found contingency management to be effective in promoting cocaine and opiate abstinence amongst buprenorphine-maintained clients with comorbid major depression [418], in promoting abstinence in a cocaine-abusing, comorbid homeless group [419], and in reducing substance use and psychiatric symptoms in stimulant users with serious mental illness [420].