The data and analyses in this report are from the first (1980) wave of information from the National Center for Education Statistics study, "High School and Beyond," a longitudinal study of U.S. high school seniors and sophomores. Data are available for 30,030 sophomores and 28,240 seniors, a total of 84 percent of the 69,662 students in the sample. Catholic schools, which constitute about two-thirds of the total private sector, and other private schools are separately compared to public schools. For some analyses 11 high-performance private schools and 12 high-performance public schools are included in the comparison. The report covers four major areas of interest in the comparison of public and private schools: student body composition, resources available, the functioning of the schools, and the outcomes for students. Findings indicate that important factors in bringing about higher scholastic achievement in private and Catholic schools than in public schools are the greater academic demands and more ordered environments. Within the public schools, students who are better disciplined and are in schools with more ordered environments also achieve more highly. Appendices contain statistical references, items from the student and school questionnaires used in the analyses, and a bibliography. (Author/MLF)