Latin American economic development has been perceived as a puzzle. The region has trailed most other world regions over the past half century despite relatively high initial development and school attainment levels. This puzzle, however, can be resolved by considering educational achievement, a direct measure of human capital. We introduce a new, more inclusive achievement measure that comes from splicing regional achievement tests into worldwide tests. In growth regressions, the positive growth effect of educational achievement fully accounts for the poor growth performance of Latin American countries. These results are confirmed in a number of instrumental-variable specifications that exploit plausibly exogenous achievement variation stemming from historical and institutional determinants of educational achievement. Finally, a development accounting analysis finds that, once educational achievement is included, human capital can account for between half and two thirds of the income differences between Latin America and the rest of the world.