This article examines how the pay gap between men and women in the federal workforce changed over the period 1988-2007 and what factors contributed to the pay gap. To do this, we use a decomposition method to analyze the most recent data available for a representative sample of federal employees. We find that the pay gap—the difference between men’s and women’s average pay before controlling for factors that affect pay—declined dramatically over the 20-year period. Most of this decline is because women and men in the federal workforce have become more similar over time in their levels of education and work experience and the jobs they perform in the federal government.