Authoritarian repression is understood as a means to eliminate dissent. Yet most dictators also require some popular support to survive. How does the need to maintain supporters influence repression? This dissertation argues that repression can serve to appeal to supporters, by signaling to a regime's backing coalition that authoritarian control is uniquely capable of managing political and social threats to the state. The three chapters bring to bear new findings on a variety of repressive methods used during Augusto Pinochet's dictatorship in Chile (1973-1989). Chapter 2 demonstrates how the need for support shapes patterns of political killings. Chile's military justified a coup on the basis of a communist threat that was, in fact, exaggerated. Original data on 3,000 victims, along with qualitative evidence, show that killings targeted suspicious individuals in otherwise high-support areas to demonstrate that a communist threat existed and the military was uniquely capable of managing it. Chapter 3 shows how supporters can constrain violence: the more prominent the opposition leader, the more likely their death or detention will mobilize opposition and alienate supporters. New data on the repression of candidates for national office shows that election -- by increasing visibility -- constrained violent repression. The regime instead substituted it with exile. Chapter 4 demonstrates that dictators can use even seemingly punitive policies to reward supporters. Text analysis of all 8,000 movies reviewed for distribution during the dictatorship shows bans largely targeted immoral content, rather than political themes. Qualitative and quantitative evidence link this to the regime's need to appeal to conservative groups. Findings provide new insight into how dictators balance security and popular support.