The study summarized in this report investigated the current nature of California's high school curriculum, how it is determined, and how it differs for different groups of students. Data were gathered from 26 representative high schools. Chapter 1 describes the six levels of curricular policy and decision making in California and the decisions made at each level. It also portrays characteristics of schools statewide and in the study. Chapter 2 addresses graduation and proficiency requirements, which are shown to have clear effects on particular cohorts of students but which do not standardize courses of study. The courses of study of three students in one school are described to demonstrate the very different paths students can pursue. Study schools are compared in academic, nonacademic, and elective course requirements. Chapter 3 describes the curriculum structure at each school which differentiates students into various instructional cohorts, each receiving a different curriculum determined by the department-level tracking system. Sample curriculum maps from study schools are analyzed. Chapter 4 outlines student placement and monitoring processes, showing how students receive varying amounts of support and examining the complexity and problems of monitoring student progress. The fifth and final chapter compares the effects of the policies and practices found in terms of the academic programs available to cohorts of students. Appendices contain the complete list of study topics and sample student programs. (CMG)