The Barro-Lee dataset provides data on educational attainment for 146 countries at 5-year intervals from 1950 to 2010. It also provides information about the distribution of educational attainment of the adult population over 15 years and over 25 years, by sex, across seven levels of education – no formal education, primary incomplete, primary complete, lower secondary, upper secondary, tertiary incomplete, and tertiary complete. The average years of schooling at all levels – primary, secondary, and higher – are also measured for each country and for regions of the world. In addition to updating and expanding our previous estimates (1993, 1996, and 2001), we have improved the accuracy of the estimates in the current version, using more information and better methodology. To reduce measurement error, the new estimates are constructed using recent census/survey observations available from consistent census data, disaggregated by age cohort and new estimates of mortality rate and completion rate by age and by schooling level.