Military organizations around the world often struggle to integrate and utilize innovative changes in tactics and technology that would save lives and enhance military power. This dissertation explains why the integration of innovations often encounters resistance. I argue that resistance is most likely when innovations disrupt existing gender hierarchies. Accounting for the relationship between gender and changes in warfare can help us understand why some innovations are harder to integrate and why some militaries struggle more than others to integrate them. Such changes can also influence the inclusion (or exclusion) regimes of militaries. This dissertation builds a broad theory of military innovation and gender. It tests the theory through a nested case comparison of the integration of two military innovations that challenge the gender status quo by reducing exposure to risk and the need for physical strength: (1) drones by the Israel Air Force and Artillery Corps, and (2) population-based counterinsurgency (COIN) by the Turkish Armed Forces and Australian Defense Force. For each case, I rely on interviews with military personnel and defense experts, as well as the analysis of government documents, military journals, news articles, field manuals, and other primary sources. I find that in both cases military organizations with higher degrees of inclusion (the Israel Air Force and Australian Defense Force) more effectively integrated new innovations than military organizations that were less inclusive. Finally, I develop and utilize an original dataset of Institutional Commitments to Inclusion (ICI) across all NATO-member and partner countries from 1991 to 2016 to examine whether innovation integration drives gender inclusion reform. Given that data on gender in militaries worldwide is limited and often inconsistent, the collection of new data required a close analysis of government reports submitted to the NATO Committee on Gender Perspectives and a range of other primary sources for each country-year. The results show that innovative change is an important factor in understanding why and when gender policy reforms take place. This study suggests that policymakers and scholars interested in military innovation and its influence on the future security environment must account for the role of gender.