Although many marijuana users do not report experiencing problems, several studies have described a range of physical, social, psychological, and legal problems associated with its use (Agosti & Levin, 2004; Budney, Radonovich, Higgins, & Wong, 1998; Haas & Hendin, 1987). Marijuana is the primary substance mentioned in adolescent arrests, emergency room admissions, and autopsy reports (Bureau of Justice Statistics [BJS], 2000; SAMHSA, 2000a, 2000b). Additionally, approximately 9% of all marijuana users will meet the criteria for marijuana dependence during their lifetime (Anthony, Warner, & Kessler, 1994). Hall, Solowij, and Lemon (1994) indicate that the risk of dependence may be particularly strong, as high as 20-30%, for individuals who use marijuana on multiple occasions.