This book uses micro-level data for 18 Latin American countries to examine the choices adolescents make in three areas of behavior: their time allocation toward school and work, their sexual behavior and fertility, and their adoption of adult roles as they marry or cohabitate. Analyzing these issues comparatively across countries provides a richer contrast of the broad range of behavior among youth around the region than traditional country studies. The analysis pays particular attention to the accumulation of human capital, a key determinant of living standards at the individual level and social progress at the aggregate level.