Why do some dictatorships establish institutions that may constrain their leaders? We argue that institutions promote the survival of dictatorships by facilitating authoritarian power-sharing. Specifically, institutions such as parties, legislatures, and advisory councils alleviate commitment and monitoring problems between the dictator and his allies caused by the secrecy in authoritarian governance. However, because authoritarian power-sharing succeeds only when it is backed by a credible threat of a rebellion by the dictator’s allies, institutions will be ineffective or break down when an imbalance of power within the ruling coalition undermines this threat’s credibility. Our arguments clarify the complex interaction between collective action, commitment, and monitoring problems in authoritarian governance. We use both historical and large-N data to assess new empirical predictions about the relationship between political institutions, leader survival, and the concentration of power in dictatorships.