This study explores how the gender and racial composition of the science, technology, engineering, and mathematics (STEM) portion of the federal workforce has changed, and how female and minority employees with STEM degrees compare with White majorities and those with degrees in non-STEM fields. Using a series of ordinary least square analyses of a 1% random sample of federal employees for 1983, 1996, and 2009, this study finds that gender and racial pay disparities have decreased over the study period, and that the extant gender pay gap can be explained largely by educational attainment, work experience, and particularly by the changing composition in STEM majors. Despite the decrease in pay disparity, a racial pay gap still remains even after controlling for education level, federal experience, and other major factors.