Following an overview of the key findings of the survey as a whole, the study design and procedures are described. A chapter on the prevalence of drug use among young adults provides a note on lifetime prevalence estimates and data on the prevalence of drug use in 1990 as a function of age, and prevalence comparisons for important subgroups (sex differences, regional differences, and differences related to population density). A chapter on trends in drug use among young adults addresses trends in prevalence through 1990 and trends for the important subgroups. Information on attitudes and beliefs about drugs among young adults focuses on the perceived harmfulness of drugs and personal disapproval of drug use. Information on the social milieu for young adults encompasses peer norms as perceived by young adults, exposure to drug use by friends and others, and perceived availability of drugs. Information on college students includes the prevalence of drug use among college students and trends in drug use among college students. Although data show that drug use among college students and young adults has decreased significantly in recent years, drug use in this population is still greater than can be found in any other industrialized nation in the world. Even by longer term historical standards in the United States, these rates remain extremely high; by their late 20's, more than 80 percent of today's young adults have tried some illicit drug other than marijuana. By age 27, 40 percent have tried cocaine. More than one in five young adults aged 19 to 28 is a daily smoker, and one in six (17 percent) smokes a half pack a day or more. 26 figures