The subjects were 189 MA users enrolled in larger ongoing studies of MA use at two study sites: Sacramento and San Francisco, California. Participants were required to be 18-65 years of age, MA-dependent, but not meeting DSM-IV criteria for current dependence on any drug other than MA or nicotine. Research assistants approached persons who reported MA use at each of the San Francisco and Sacramento, California sites, and explained a written informed consent form that detailed study procedures, risks, and benefits. All subjects completed the same consent process. Institutional Review Boards approved consent forms, subject compensation, and the study protocol.
