This paper evaluates the e↵ect of territorial autonomy on the out- break of internal conflict by analyzing ethnic groups around the world since WWII. Shedding new light on an ongoing debate, we argue that the critics have overstated the case against autonomy policies. Our evidence indicates that decentralization has a significant conflict- preventing e↵ect where there is no prior conflict history. In post- conflict settings, however, granting autonomy can still be helpful in combination with central power sharing arrangements. Yet, on its own, post-conflict autonomy concessions may be too little, too late. Accounting for endogeneity, we also instrument for autonomy in post- colonial states by exploiting that French, as opposed to British, colonial rule rarely relied on decentralized governance. This identification strategy suggests that na¨ıve analysis tends to underestimate the pacifying influence of decentralization.