Treatment admissions for marijuana dependence have doubled over the past 5 years and now comprise 27 percent of all drug abuse admissions. Yet treatment research on marijuana dependence remains sparse as only one controlled trial appears in the peer- reviewed literature. Our group has established a marijuana treatment clinic to research strategies for providing effective treatment. An initial trial showed that an abstinence-based voucher program combined with behavioral counseling produced greater periods of marijuana abstinence than behavioral counseling alone. That study was the first randomized trial to demonstrate the efficacy of a voucher program for marijuana dependence and added to the literature establishing voucher programs as effective treatments for drug dependence. The primary aim of this proposal is to continue the development of behavioral interventions for marijuana dependence with the ultimate goal of creating cost-effective, empirically-based treatments. The experiment proposed in this application will extend the findings of the initial trial by comparing the effects of three interventions: the voucher program combined with behavioral counseling, behavioral counseling alone, and the voucher program alone. The specific aims of this study are to: (1) systematically replicate and extend the efficacy of the voucher program for increasing marijuana abstinence when added to behavioral counseling; (2) determine if behavioral counseling enhances the effect of the voucher program; (3) determine if the voucher program is effective when provided without counseling; (4) determine the longer-term, post-treatment effects of these treatments. This experimental strategy of conducting systematic replications in the context of programmatic extensions of previous findings has been effective in our cocaine treatment research, and thus is being adopted with this proposed marijuana research. By adding a vouchers-alone treatment group, increasing sample sizes, and conducting a systematic one-year follow-up, the proposed study will provide a more rigorous test of the efficacy of the interventions than the initial trial. Voucher programs may offer a method for improving drug abuse treatment outcomes either alone or in conjunction with pharmacological or psychological interventions. Given the "novelty" of such programs, it is vital to our dissemination mission that we clearly establish the reliability and validity of their short and long-term efficacy.