During the height of the exclusion era, when Asian immigrants were prohibited from naturalizing and becoming United States citizens, state and federal court judges around the country naturalized at least 500 Asian immigrant servicepersons and veterans. Between 1918 and 1925, Federal Bureau of Naturalization officials and state and federal court judges had to determine whether the military naturalization provisions enacted in 1918 included the same racial restrictions that the general naturalization provisions included. This Article tells the story of how these officials and judges navigated statutory text, congressional intent, and the reality of Asian immigrant membership in the United States Armed Forces to determine the role that race vis-à-vis military service should play in determining citizenship eligibility. The story of Asian immigrant naturalization between 1918 and 1925 highlights a long-standing question within American citizenship and immigration law: how to measure an applicant’s adoption of and commitment to mainstream American values, norms, and practices. Are there accurate and reliable categories that measure cultural assimilation and allow for cost-effective and efficient decision-making? Alternatively, are categories sufficiently inaccurate and unreliable such that individualized assessments of specific cultural criteria offer the only legitimate approach? Based on administrative memos, state and federal court judicial opinions, and newspaper articles, this article reveals how state and federal court judges struggled with this general question and how the Supreme Court resolved the split that existed across the country. United States naturalization law continues to require category-based decision-making, and it is important that we similarly interrogate those categories to determine the extent to which they accurately and reliably measure the intended naturalization criteria.