This paper presents new results on the relationship between education expansion and income inequality. While human capital theory suggests that income inequality increases with inequality of education outcomes, the expected relationship between income inequality and the level of education is ambiguous. Consistent with these theoretical priors, when dynamic panel estimation techniques are used to address issues of persistence and endogeneity we find a large, positive, statistically significant and stable relationship between education inequality and income inequality, especially in emerging and developing economies and among older age cohorts. The relationship between income inequality and education levels is positive but small and not always statistically significant, but we find a statistically significant negative relationship with schooling levels of younger cohorts. Statistical tests indicate that our dynamic estimators are consistent and that our identifying instruments are valid. Policy simulations suggest that education expansion will continue to be inequality reducing but that this role will diminish as countries develop.