Contingency management (CM) interventions represent one treatment approach that has great potential to effectively motivate and facilitate change in this challenging clinical population. CM interventions are based on extensive basic-science and clinical-research evidence demonstrating that drug use and abuse are heavily influenced by learning and conditioning and are quite sensitive to systematically applied environmental consequences. Behavioral-analytic theory and the empirical literature on behavior change in general suggests that the efficacy of CM interventions is influenced by the schedule used to deliver consequences the magnitude of the consequence, the choice of the target behavior, the selection of the type of consequence, and the monitoring of the target behavior. The chapter uses examples from cannabis CM program to describe these basic principles and illustrate their application. Almost half of those seeking treatment for marijuana abuse have criminal justice involvement and are referred to treatment by the legal system.