This article argues that military intervention into politics can only be understood by studying both the nature of threats and of domestic political arrangements. I offer a theory of the military in politics built around the interaction between threat configuration, political institutionalization, and civilian government legitimacy. The argument is tested with paired-comparison case studies of Indian and Pakistani civil-military relations since independence. Despite their similarities at the time of partition, these two militaries took completely different political trajectories. The cases reveal how structures of domestic politics interact with military threat perceptions to explain civilians' ability to maintain varying levels of control over the military.