Human capital is central to efforts to promote growth, convergence, and the elimination of poverty. Drawing on the seminal macroeconomic frameworks by Nelson-Phelps, Lucas and subsequent developments, alongside macro and microeconomic evidence, we examine the role of human capital in driving innovation and growth. We highlight how different types of human capital, characterized by education level, matter in different stages of development. Despite documented increases in years of schooling, the world’s poorest regions still see stagnating outcomes in learning and education quality, potentially creating poverty traps where investments in neither physical nor human capital materialize. We discuss obstacles to human capital accumulation through a simple analytical framework and present evidence from randomized interventions spanning early childhood programs to school-age initiatives, assessing policies that can effectively remove barriers to skill acquisition and establish foundations for sustained growth.