International cooperation on issues of security is a central concept in many theoretical debates in international relations. This dissertation is an attempt to lay the foundation for measuring military cooperation and understanding the forces brought forth through its expansion. The central notion is that the set of policies related to military cooperation should be studied as a coherent whole. The network map of military cooperation is drawn to include the various cooperative behaviors and institutions that comprise the concept, and military cooperation is estimated as a latent dyadic trait. Data on one behavior--joint military exercises--is systematically collected and presented for the First time. Other indicators are gathered from existing sources, and all are combined to estimate military cooperation using methods from item response theory. Measuring international military cooperation as a latent trait provides insight into many critical research questions because these relations, as a whole, in influence and structure state behavior. The causal mechanism associated with such in influence is related to the role of the military, and in particular its autonomy and the linking of security provision among states. Two examples where such cooperation in influences state behavior are with respect to the state's ability to intervene abroad and, in the event of social unrest, the state's decision to use lethal repression domestically. The multi-policy approach is used to derive a new measure of foreign policy similarity, which is compared to previous measures and is shown to be more intuitive and empirically different. At the system level, as states integrate their security structures, they form communities of military cooperation. These communities, too, affect state behavior along various dimensions. One example is through foreign policy transmission, the process by which a state transmits its preferred policy to other, more capable or willing members of their community. Provided the integration is deep enough, communities act as single entities with behaviors unto themselves. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]