This volume covers (a) the prevalence and frequency of drug use among American secondary school students (specifically, in 8th, 10th, and 12th grades) and (b) historical trends in use by students in those grades. Distinctions are made among important demographic subgroups in these populations based on gender, college plans, region of the country, population density, parents' education, and race/ethnicity. Data on grade of first use, trends in use at lower grade levels, as well as intensity of drug use are also reported in separate chapters. This study has demonstrated that key attitudes and beliefs about use of the various drugs are important determinants of trends in use over time. Therefore, they are also tracked over time, as are students' perceptions of certain relevant aspects of the social environment-in particular, perceived availability, peer norms, use by friends, and exposure to use of the various drugs.