This paper reports the results of a large-scale study on the school environment and its influence on the academic achievement, values, and aspirations of students. The study (1) identifies a number of dimensions of educational and social climates of high schools, (2) assesses the effects of these dimensions on the academic performance and college plans of students, and (3) investigates the sources of these effects on the achievement and college plans of students by controlling formal organizational properties of school- and community-level variables. Statistical analysis was performed on data derived from questionnaires and aptitude tests administered to 20,345 students, 1,029 teachers, and 20 principals in 20 public, coeducational high schools in eight States spread over seven different geographical areas. Results of the study show that the educational and social environment of the school does have a moderate effect on the academic behavior of students and that the research design used holds much promise for future research in the area. (TT)