The authors argue that cannabis use continues to receive considerable attention by policymakers and researchers in the United States because it is the most widely used and treated illicit drug, this introduction presents a series of statistics illustrating marijuana usage in the United States. Contending that according to the 2000 United States National Household Survey on Drug Abuse, 1.6 million Americans meet the criteria for being classified as dependent on cannabis, with 1.2 million additional Americans meeting the criteria for abusing cannabis, the authors maintain that 713,000 of these individuals sought treatment for cannabis use in 2000. This introduction briefly discusses the Youth Treatment Study with adolescent substance users and the Marijuana Treatment Project with adult substance users and abusers. In conclusion, the authors state that the Center for Substance Abuse Treatment believes that by funding substance use and abuse projects, they are able to fundamentally alter the ways that experts, treatment clients, and the general public view cannabis abuse treatment. References