"Throughout recent history, the U.S. military has served as a model for racial integration and has seen diversity flourish in its organization. Still, while the enlisted ranks of the U.S. military exhibit a high level of demographic diversity, the leadership of the military has remained demographically homogenous. This report summarizes findings from an exploratory study of a potential barrier to improving demographic diversity in the senior officer ranks. We started with an observation that officers with combat-related career backgrounds, such as the Combat Arms branches of the U.S. Army, tend to populate the top levels of the Army. In 2006, for instance, 80 percent of Army generals were in Combat Arms branches. We also observed that minority officers are disproportionately absent in these key career fields. This report touches on the career field assignment processes for all services and commission sources. We found that each military service (Army, Air Force, Navy, and Marine Corps) and commission source (Reserve Officers' Training Corps [ROTC], service academy, and officer training school/officer candidate school) has a distinct career field assignment process. However, because we had limited resources, we concentrated on the Army ROTC process as a detailed case study. As a case study, its results are not fully generalizable to other services or even to other commission sources within the Army. Our primary aims are to highlight the importance of the issue and to motivate the U.S. military to conduct a comprehensive study of the issue." -- p. xi.