Using Panel Study of Income Dynamics (PSID) data, the authors analyze changes in wage differentials between white men and women over time and across the entire wage distribution. The authors decompose distributional changes in the gender wage gap to assess the contribution of observed characteristics measuring individual productivity. They find that the gender wage gap narrowed by 16% at the lowest decile and by less than 5% at the highest decile. The decomposition results indicate that changes in the gender wage gap are mainly attributable to changes in educational attainment at the top of the wage distribution, with a sizable part due to work history changes at the bottom. The findings further reveal that the accuracy of the results depends on the direction in which the decompositions are performed.