When authoritarian regimes break down, why does communal violence spike and why are some locations more prone to violence than others? To understand violence during transitions, it is necessary to understand what sustains order when regimes are stable. While existing theories attribute order to formal or informal security institutions on their own, I argue that intercommunal order obtains when formal and informal security institutions are aligned. During authoritarian breakdowns, the state's coercive grip loosens, exposing mismatches between formal and informal institutions and raising the risk of communal violence. Formal-informal mismatches emerge in communities accustomed to heavy state intervention since they will have developed more state-dependent informal security institutions. I apply an instrumental variables approach on a nationwide dataset of village-level data to show that prior exposure to military intervention, proxied by the distance to security outposts, led to Indonesia's spike in violence during its recent democratic transition.