Who Watches the Watchers is an incisive exploration of the guardianship dilemma in authoritarian regimes. Dictators must rely on coercive agents for repression, but doing so creates a problem: coercive agents themselves can become a threat to the dictator’s survival. With this tension in mind, Henry Thomson explores the differences in the coercive capacity of Communist dictatorships in Eastern and Central Europe, some building expansive secret police agencies, putting a pre-emptive mass repression model into practice, and successfully enforcing social order, others failing to do so. Thomson argues that the cohesion of authoritarian elites is at the heart of this variation. When cohesive, authoritarian elites can act collectively and successfully monitor and discipline coercive agents, allowing for investments in coercive capacity. When there are divisions among authoritarian elites, oversight of coercive agents is hampered, limiting the expansion of secret police forces. Thomson tests this argument with an innovative multi-method difference-in-differences research design. Using Stalin’s death as a natural experiment, he explores how this shock reduced the cohesion of some authoritarian ruling coalitions. Paired comparative historical case studies of East Germany and Poland trace the causal logic of the argument and its implications for social order. Complementing the rich case studies, Thomson uses cross-national statistical analyses to document longer tenures for security officials and growth in terms of staff and informants in cases that maintained elite cohesion in the wake of Stalin’s passing. The book offers compelling theoretical insights, and a careful exploration of qualitative and quantitative evidence. It should be of great interest to anyone studying authoritarian politics and the political transitions of Eastern Europe.