This book explores the consequences of the abandonment of formal tracking systems in U.S. high schools, and how or whether this dramatic change provided students with the educational opportunity and mobility previously denied them. Drawing on nationally representative data and sophisticated methodologies, this book examines how the contemporary curricular structure works, including the scope of the structure, mobility and social patterning within this structure, and the consequences of an individual's socially patterned location for college entry and career path. The chapters are: (1) "Introduction"; (2) "Course Taking after the Decline of Formal Programs"; (3) "Merit and Track Placement"; (4) "SocioeconomicDiversity, School Environment, and Track Structure"; (5) "Is Tracking a Tournament?"; (6) "Individual-Level Factors in Curricular Mobility"; (7) "Selected Effects of Curricular Location"; and (8) "After the Unremarked Revolution: Summary and Conclusions." Appendixes contain discussions of measuring track location, log linear models, and strategies of analysis. (Contains 27 tables, 6 figures, and 179 references.) (SLD)