This report is based on the Schools and Staffing Survey (SASS) of 1987-88 and 1990-91 and is designed to provide a broad picture of private schools in the United States. The SASS collects data on only a sample of private schools, but collects a much richer picture of each participating school than does the Private School Universe Survey, a supplement to the Common Core of Data. In 1990-91, the SASS found that there were approximately 24,690 private elementary and secondary schools in the United States, serving an estimated 4,673,878 students in kindergarten through grade 12. This suggests that nearly one-quarter of the schools in the nation are private, and that 1 out of every 10 students are in private schools. Findings from the SASS are presented in sections on: (1) characteristics of private schools as units; (2) characteristics of students; (3) characteristics of teachers and principals; (4) educational goals of teachers and principals, their perceptions of school climate, and rates of graduation and college attendance; and (5) descriptive profiles by religious or other affiliation. Ten figures and 44 figures present survey findings. Two appendixes contain tables of standard errors and technical notes. (Contains 31 references.) (SLD)