This study examined how high schools made decisions about which courses to offer and which courses were appropriate for various students. During year 1, researchers visited three senior high schools in a major West Coast urban center to observe, study school documents, and talk with educators and students about curriculum offerings and student assignment practices. During year 2, researchers analyzed transcripts from students in the 1988 senior classes to track the effects. According to field study findings, all three schools made assumptions about the abilities, aspirations, and educational "needs" of incoming students that guided decisions about course offerings and were the basis for student placement policies. Assumptions were also related, in large part, to students' race and family socioeconomic status. Background characteristics influenced decisions about individual student placement. Transcript analyses showed low-income and disadvantaged minority students took more vocational courses, particularly more occupationally oriented courses. Heavy vocational education participation was largely reserved for the least academically able students. Achievement was highly related to academic course participation, but students' race/ethnicity was often important to participation. Findings showed a lack of attention paid to vocational education and a strong need for integrated academic and vocational curricula. (Appendixes include additional student characteristics, vocational course categories, supplementary tables, methods and results from logistic analyses, and 36 references.) (YLB)