Marijuana dependence is one of the most common substance-related disorders in the United States. Despite its prevalence, there is a lack of clinical research addressing treatments for marijuana dependence. Research has shown that marijuana abuse is associated with affective disorders. This may be caused by repeated use for relief from anxiety. The use of an anxiolytic agent, a drug that relieves anxiety, may help treat marijuana dependence. Motivational enhancement therapy has been shown to reduce marijuana use. Therefore, it is likely that buspirone, which is an anxiolytic agent, combined with motivational enhancement therapy will prove beneficial in treating marijuana dependence. This study will assess the effectiveness of a combination of buspirone and motivational interviewing in the treatment of marijuana dependence.