Over the past quarter of a century, the Monitoring the Future study has tracked young American's use of psychoactive substances, both illicit and licit. In this volume, findings are presented on the prevalence and trends of drug use and related factors for secondary school students (eight, tenth, and twelfth graders). Distinctions are made among demographic subgroups of these populations based on gender; college plans; region of the country; population density; parents' education; and race/ethnicity. This study demonstrates that key attitudes and beliefs about use of the various drugs are important determinants of trends in use over time. Attitudes are tracked as well as students' perceptions of certain relevant aspects of their social environment, including perceived availability of substances, peer norms, use by friends, and exposure to use. Chapter One provides an introduction. Chapter Two gives an overview of key findings. Chapter Three presents study design and the procedures. Chapter Four discusses the prevalence of drug use among the different grades. Chapter Five explains trends in drug use. Chapter Six looks at the incidence of drug use in the lower grades. Chapter Seven discusses the degree and duration of drug-induced highs. Chapter Eight details attitudes and beliefs about drug use. Chapter Nine includes the influence of the social milieu. Chapter Ten explains other findings from the study. (Contains 5 appendixes, 152 tables, 105 figures, and references.) (JDM)