Prior to 1994, there were no published reports of controlled trials of treatment for marijuana use disorders. The authors argue that recent findings demonstrating the increasing prevalence of marijuana dependency and its associated consequences indicate the growing need for empirically validated treatments for substance abusers. Focusing on the Marijuana Treatment Project, this article describes this multi-site study conducted in Connecticut, Washington, and Florida, which randomly assigned program participants into either 9-session cognitive behavioral therapy (CBT) treatments with motivational enhancement therapies (MET) and case management (CM) components, a 2-session MET intervention, or a delayed treatment control (DTC). After describing the 450 program participants, 18-years-old and older, the authors argue that these individuals met diagnostic criteria for cannabis dependency and voluntarily presented for outpatient treatments. Assessing whether the randomization procedure yielded comparable groups, the different treatment conditions were compared on all baseline measures using one-way analysis of variance. The authors found that the program participants who smoked marijuana multiple times a day for 15 years or more reported multiple dependence symptoms and negative consequences related to marijuana use. The authors conclude that the growing awareness of the need for treatments for adult marijuana dependence demonstrates the need for empirically validated treatment programs. Tables, references