Cognitive-behavioral coping skills therapy (CBT) is a widely used and recognized treatment that has been empirically validated for a range of substance use disorders, often with emergent effects and continuing improvement even after treatment ends. Treatment retention and compliance are associated with enhanced treatment outcomes in CBT. Contingency management (CM) also has very strong support and is associated with rapid, robust effects on targeted outcomes. Despite their many strengths, neither CBT nor CM is universally effective. It is now essential to seek strategies to maximize and extend the effectiveness of these two approaches and to better understand how these treatments exert their effects.

The investigators propose to evaluate targeted strategies to maximize the effectiveness of CBT and CM, respectively. To maximize the effectiveness of CBT, the investigators will evaluate the benefit of adding CM, with reinforcement for session attendance and homework completion, to standard individual CBT for outpatient marijuana abusers, in order to expose participants to more skill training and opportunities for practice of skills. To maximize the effectiveness and durability of CM, we will evaluate the benefit of integrating it with skills training, specifically designed to reduce drop off effects, in order to extend CM's benefits beyond the active treatment period. We propose to conduct a Stage II trial which will: (1) Evaluate the efficacy of four conditions for 160 marijuana dependent outpatients: (a) Standard CBT, (b) CBT with CM reinforcement for attendance and completing homework (CBT+CM/adherence), (c) CM for abstinence alone (CM/abstinence), (d) CM for abstinence integrated with CBT (CM/abstinence+CBT), and (2) Evaluate the longer-term durability and / or delayed emergence of treatment effects after termination of the study treatments through a one-year follow-up. Secondary aims will be to conduct (a) detailed process studies to evaluate whether the proposed enhancements affect proximal and distal outcomes as hypothesized and (b) economic analyses. Study treatments will last 12 weeks.

Inclusion Criteria:

• 18-65 year old marijuana dependent
• willing to sign consent
• no use of prescribed psychotropic drugs
• willing to give three individuals as contacts
• willing to accept randomization
• read and write English (third grade level)

Exclusion Criteria:

• unable to commit to 1 year follow up