Approved for public release, distribution is unlimited / The authors examine the history of immigrant military service in the United States, explore the motivations of noncitizen enlistees, and analyze the military performance of noncitizens relative to that of citizen enlistees. Information sources include a comprehensive review of literature, focused interviews with a small sample of noncitizen enlistees, and cohort data files of enlisted personnel who entered the military from 1990 through 1998. The history of noncitizen service corresponds roughly to the nation's history of immigration and naturalization policy, with military service having offered immigrants economic benefits, as well as a path toward assimilation. Service by noncitizens has also provided the country a way to meet its military manpower needs. The results of statistical analyses suggest noncitizens have lower predicted rates of first-term attrition, and higher estimated rates of retention beyond the first term and promotion to E-4. The authors conclude that noncitizens provide a valuable source of manpower, and fulfill important roles as influencers for the next generation. Thus, it may be worthwhile to provide noncitizens more information about enlistment opportunities, and to implement unique reenlistment incentives including expedited green-card status for family members. Future research should examine specific ethnic categories of interest within the population of noncitizens. / First Lieutenant, Turkish Army / Lieutenant Commander, United States Navy