This study examines the management of ethnic and social diversity in the military by comparing the United States of America, a reference case, and Saudi Arabia, which is still in an early stage of institutionalization. It uses a military-sociological approach, which posits that the military reflects the socio-cultural structure of society. It focuses on four key societal indicators: ethnicity, gender, sectarian affiliation, and tribal identity. It argues that the effectiveness of diversity management depends on integrating both normative (legislation and policies) and practical (implementation) levels, while accounting for the societal specificity of each case. The US experience shows that the presence of both normative and practical frameworks does not necessarily yield an ideal type, due to persistent representation challenges, particularly at senior military ranks. In contrast, the Saudi case is characterized by the absence of a clear normative framework and the novelty of the experience, despite emerging indicators of openness, especially after 2017. The study concludes that managing diversity is not merely a social demand, but also a prerequisite for strengthening military effectiveness and institutional cohesion.