To develop and harness technological capabilities to meet its missions, the U.S. Department of Defense (DoD) seeks ways to improve acquisition and retention of technical talent from science, technical, engineering, and mathematics (STEM) disciplines. Congress and DoD policymakers point to higher compensation in the private sector as a key challenge. However, a prior RAND Corporation report suggests that the average compensation difference between private- and public-sector STEM workers is not that large when workforce characteristics are considered. This same research shows that there are demographic-group differences (gender, racial and ethnic) in compensation for STEM workers. Given Congressional and DoD interest in employing more STEM workers-and federal government interest in promoting diversity, equity, inclusion, and accessibility more generally-demographic-group differences in the DoD STEM workforce warrant in-depth understanding. Building on previous RAND research, the authors use several years of DoD civilian workforce data to quantify trends in demographic-group compensation differences and other employment-related outcomes among the DoD civilian STEM workforce. The authors provide an overview of the composition of the DoD civilian STEM workforce, then perform an analysis that controls for observable characteristics, such as education, that might explain those group differences. Next, they describe the compensation implications of the demographic composition of civilian pay plans and explore compensation differences while holding DoD component, geographic location, and STEM occupational category constant. They conclude with key findings and recommendations for DoD to better understand and address demographic-related inequalities within its STEM workforce.