The gender gap reversal in educational attainment is ubiquitous in high-income countries, as well as in a growing share of low- and middle-income countries. To account for the reversal, this paper proposes a theoretical framework in which the interplay between the distributions of academic aptitudes and changes in the net benefits of schooling over time affect the gender composition of those getting more schooling. The framework is used to formulate and test alternative hypotheses to explain the reversal. The paper introduces the tail dynamics hypothesis, which builds on the lower dispersion of academic achievement among females observed empirically. It also studies the mean dynamics hypothesis, which is based on previous literature. Both hypotheses can explain the reversal in this framework. However, the assumption behind the tail hypothesis is better supported by the data. Its predictions are also consistent with gender differences in Scholastic Achievement Test score dynamics and in international test score distributions that cannot be explained by previous theories.