The paper presents a new dataset for years of schooling across countries from 1960 to 2000, constructed from the OECD database on educational attainment and UNESCO surveys. The improved quality of the data, particularly in terms of uniform classification systems and detailed age group information, allows for a more accurate representation of human capital. The authors argue that this new dataset can replace Barro and Lee’s (2001) data in empirical research. They find that their series yield significant coefficients for schooling in standard cross-country growth regressions and are also significant in panel data estimates, even when accounting for physical capital accumulation. The estimated macro return aligns with labor studies, differing from earlier literature due to reduced measurement error. The paper discusses the conceptual and empirical challenges in measuring human capital, highlighting the need for a clear definition and high-quality data. The authors' approach, which uses detailed age group information and consistent classification systems, significantly reduces measurement errors.The paper presents a new dataset for years of schooling across countries from 1960 to 2000, constructed from the OECD database on educational attainment and UNESCO surveys. The improved quality of the data, particularly in terms of uniform classification systems and detailed age group information, allows for a more accurate representation of human capital. The authors argue that this new dataset can replace Barro and Lee’s (2001) data in empirical research. They find that their series yield significant coefficients for schooling in standard cross-country growth regressions and are also significant in panel data estimates, even when accounting for physical capital accumulation. The estimated macro return aligns with labor studies, differing from earlier literature due to reduced measurement error. The paper discusses the conceptual and empirical challenges in measuring human capital, highlighting the need for a clear definition and high-quality data. The authors' approach, which uses detailed age group information and consistent classification systems, significantly reduces measurement errors.