The decade of the 1980s saw great change in the educational system. This report examines the changing demographics of high school students over the last decade and investigates the impact that these changes may have had on high school dropout rates. Specifically, the study examined the changing nature of the high school population during the last decade and describes the different effects of various student-level characteristics on the propensity for students to drop out of school between 1980 and 1982 compared to 1990 and 1992. The report provides data that depict changes in the characteristics of students' families, in students' economic backgrounds, in dropout rates, and in the characteristics of dropouts. Data show that during the 1980s, a growing number of students with characteristics traditionally associated with school failure began attending high school; at the same time, high school dropout rates decreased by almost 50 percent. The declines occurred among students with a variety of characteristics--minority and majority students, students in intact families and nonintact families, and students with children of their own living in their household. Many groups of students traditionally considered "at risk" for school failure dropped out at lower rates in 1990 than in 1980. However, there were other groups of students whose dropout rates did not improve. These were students from poor families, who had histories of poor academic achievement, and who had multiple risk factors in their backgrounds. The study used data on two cohorts of high school sophomores collected by the National Center for Education Statistics--the sophomore cohort of 1980 from the High School and Beyond (HS&B) study, and the sophomore cohort of 1990 from the National Education Longitudinal Study of 1988 (NELS:88). Appendices contain methodological notes, standard error tables, and multivariate analyses. Eight figures and 57 tables are included. (LMI)