In hierarchies, agents’ hidden actions increase principals' transactions costs and give rise to a demand for monitoring and enforcement. The fact that the latter are costly raises questions about their scope, organisation, and type. How much control is enough? The paper uses historical records to examine Stalin’s answers to this question. We find that Stalin's behaviour was consistent with his aiming to maximise the efficiency of the Soviet system of control subject to the loyalty of his inspectors and the risk of a “chaos of orders” arising from parallel centres of power.