This report is the 11th in an annual series reporting the drug use and related attitudes of America's high school seniors and young adults. The findings, which cover the high school classes of 1975 through 1987, come from an ongoing national research and reporting program entitled "Monitoring the Future: A Continuing Study of the Lifestyles and Values of Youth," conducted by the University of Michigan's Institute for Social Research. The opening three chapters review the design and content of the "Monitoring the Future" study, provide an overview of key findings, and describe the study design and procedures. Chapters 4 through 9 focus on high school seniors, providing data on prevalence and trends in drug use, use at earlier levels, degree and duration of drug highs, attitudes and beliefs about drugs, and the social milieu for seniors. Chapters 10 through 13 cover the prevalence, trends, attitudes, and social milieu of post-high school young adults, while chapters 14 and 15 focus on prevalence and trends in drug use among college students. Chapter 16 provides other findings from the study, including the use of nonprescription stimulants, daily marijuana use, and data correlating drug use with other factors. Estimates adjusted for absentees and dropouts are appended. (TE)