Stephens, R.S., Roffman, R.A., & Curtin, L. (2000). Comparison of extended versus brief treatments for marijuana use. Journal of Consulting and Clinical Psychology, 68, 898-908. American Psychological Association (ISSN: 0022-006X) Submitted: June 8, 1999 Revised: February 7, 2000 Accepted: February 11, 2000 DOI: 10.1037/0022-006X.68.5.898 'This article may not exactly replicate the final version published in the APA journal. It is not the copy of record. Comparison of Extended Versus Brief Treatments for Marijuana Use. Robert S. Stephens, Roger A. Roffman & Lisa Curtin ABSTRACT Adult marijuana users (N = 291) seeking treatment were randomly assigned to an extended 14- session Cognitive–behavioral group treatment (relapse prevention support group; RPSG), a brief 2-session individual treatment using motivational interviewing (individualized assessment and intervention; IAI), or a 4-month delayed treatment control (DTC) condition. Results indicated that marijuana use, dependence symptoms, and negative consequences were reduced significantly in relation to pretreatment levels at l-, 4-, 7-, 13-, and 16-month follow-ups. Participants in the RPSG and IAI treatments showed significantly and substantially greater improvement than DTC participants at the 4-month follow-up. There were no significant differences between RPSG and IAI outcomes at any follow-up. The relative efficacy of brief versus extended interventions for chronic marijuana-using adults is discussed. Keywords: Cognitive Therapy | Individual Psychotherapy | Marijuana Usage | Motivational Interviewing | Treatment Duration | Brief Psychotherapy Acknowledgement: This research was supported by National Institute on Drug Abuse Grant 2 R01 DA03586-04. We thank Bonnie Cleaveland, Deborah DeWolfe, and Jennifer Wertz for important contributions to the conduct of this study.