Over the past decade, club drugs, which include drugs such as MDMA (ecstasy), ketamine, Rohypnol, and GBH, have emerged as major substances of abuse among young adults. Surveys have indicated a sharply increasing use of MDMA among high school and college-aged youth. National surveys that track general drug trends are of limited use in understanding the use of club drugs for several reasons: use of these drugs varies by region; the surveys inquire about a limited range of drugs, mainly MDMA and LSD; and the studies fail to provide information about the venues linked specifically to these drugs. This study was an attempt to understand the prevalence, correlates, risk factors, and context of club drug use in a general population survey. Data were obtained from a survey of English-speaking adults, ages 18-40, who resided in Chicago. A total of 627 surveys were completed between June 2001 and January 2002. The study obtained weighted prevalence estimates of life-time, past 12 months, and past 30 day use of any club drug and of specific club drugs; prevalence of rave attendance, other drug use, and motivation for use among users; and chi-square tests of significance, logistic regression, and adjusted odds ratios. Findings indicate that overall, club drug prevalence rates were nearly twice those obtained for MDMA alone. Club drug users were more likely to use multiple illicit substances and to report having been in treatment for substance use. A majority of lifetime club drug users never attended a rave although rave attendees were more likely to report frequent use of MDMA. Significant associations were found between lifetime club drug use and gender, race/ethnicity, and sexual orientation. As indicated by these findings, prevention research should be informed by further population-based research on club drug use. Research should not focus exclusively on rave attendees, as they are only a subset of club drug users. Future research needs to articulate more clearly consumption patterns and identify key risk that can be successfully targeted. Study limitations are discussed. 6 tables, 1 figure, and 36 references