This chapter introduces the most comprehensive dataset to date on global education, encompassing both schooling years and learning outcomes. By integrating these two dimensions, we develop the Learning-Adjusted Years of Schooling (LAYS), a measure that reflects not just quantity but quality. Covering more than 120 countries from 1970 to 2020, our panel dataset harmonizes international and regional achievement tests into comparable indicators. The results highlight sharp discrepancies between years spent in school and actual learning, exposing persistent inefficiencies and inequalities across education systems. Ultimately, the project provides policymakers and researchers with robust tools to evaluate human capital, design more effective reforms, and connect education more directly to long-term economic growth.