The name "club" drugs has been applied to substances that have been typically used at "raves" and dance parties. The grouping of these drugs together in a single category because of the location of their use may obscure the fact that each of the drugs has very different pharmacological, psychological, and physiological properties, and there are important differences in the characteristics of the people who use each of the drugs, as well as in the patterns of their use. In examining the features and use patterns of each of the drugs, data were obtained from the Community Epidemiology Work Group, the Monitoring the Future Survey, the National Survey on Drug Use and Health, the Drug Abuse Warning Network, and the National Forensic Laboratory Information System. The data indicate that although "club" drugs as a group have attracted significant national attention, other than methamphetamine, they constitute a very small portion of the drug abuse problem in the United States. The use of methamphetamine continues to increase while the use of LSD, Rohypnol, ketamine, GHB, and ecstasy is apparently decreasing, although the decreases in the use of ketamine and GHB are less evident. This report recommends that prevention efforts continue to focus on perceptions of risk, peer disapproval, and availability. The users of "club" drugs differ in their sociodemographic characteristics, patterns of multiple drug use, and reasons for drug use (psychic effects compared with dependence). Prevention and treatment activities should be tailored to these differences. The levels of concomitant use of cocaine by users of ecstasy, GHB, ketamine, LSD, methamphetamine, and Rohypnol, along with the levels of use of heroin by ketamine and LSD users are matters of concern regarding the magnification of treatment needs. Overdose was either the first or second reason for "club" drug users to seek care in a medical emergency facility; this suggests the need for specialized protocols for treating each of the drug types in the acute care setting. The medical and behavioral treatment protocols must take into account the pharmacological effects of each drug as well as the characteristics of each client. 10 exhibits and 10 references