This monograph, a revision of a report prepared pursuant to a contract with the Commission on Civil Rights, discusses neighborhoods and schools, primary school variation in cognitive development, father absence and school achievement, neighborhood and school segregation, later effects of school segregation, self-concept, aspirations, and behavioral deviance. Questionnaire data were collected from stratified random samples of 17,000 students attending 11 public junior and senior high schools in Western Contra Costa County in the spring of 1965. The final sample comprised 4,077 students. Major substantive findings of the study were as follows: variations in elementary school context make a substantial and significant difference in subsequent academic success at higher grade levels; socio-economic and racial characteristics of students' age-mates have no effect independently on academic achievement of students attending similar schools; social class composition of a school affects the academic development of both Negro and white students in racially segregated or integrated situations; and, given similar social class compositions, racial balance of a school has slight bearing on the academic performance of students. (JM)