Why, how, and with what consequences do national governments delegate political authority to supranational institutions? Contrary to the static conceptions of delegation that dominate the existing literature, this article adopts a dynamic approach, where the stages of the delegation process are integrated into a coherent rational institutionalist framework. With demonstrations from the case of the European Union, the article argues that: (1) the expected consequences of delegation motivate governments to confer certain functions to supranational institutions; (2) the nature of these functions influences the design of mechanisms for controlling the institutions; (3) institutional design shapes the consequences of delegation by facilitating or obstructing attempts by the institutions to implement private agendas; and (4) the consequences of previous rounds of delegation affect future delegation, institutional design, and interaction, through positive and negative feed-back loops.