Why do militaries intervene in politics in some countries and not in others? Existing theories of civil-military relations do not adequately explain military politics around the world. This dissertation provides an alternative, political-economy explanation and argues that strength of property rights instituted by a state shapes the degree of civilian supremacy over its military. I show that secure property rights induce efficient allocation of resources and contribute to sustained economic growth, which helps accommodate group interests and increases trust among them. This helps create consensus among individuals and groups on the institutions of the state, which increases the legitimacy of the state and the credibility of its institutions. High levels of legitimacy and credibility of civilian institutions enable the state to make policy decisions independent of the military, thereby reducing the ability of the military to intervene in politics. Secure property rights also constrain the arbitrary behavior of the state to politicize the military and inspire the state to uphold merit-based, professional norms in the armed forces, which prevent spillover of social cleavages into the ranks of the military. This reinforces military professionalism and helps reduce the disposition of the military to intervene in politics. Finally, secure property rights provide incentives to the groups to uphold existing institutions and pursue their interests through the markets. As a result, groups refrain from “knocking on the door” of the military to secure their interests, which reduces the opportunity for the military to intervene in politics.