Consider the following facts. In 1950 rich countries attained an average of 8.1 years of schooling whereas poor countries attained 1.3 years --a 6-fold difference. By 2005, the difference in schooling declined to 2-fold even though the per-capita income gap did not decrease. What explains...

Three central observations motivate this paper. First, there is little variation in the fraction of unskilled workers between rich and middle income countries. This occurs despite well-known, large differences in output per worker. Among a set of rich countries, unskilled workers 25 and older,...