The European Union is composed of its fifteen member governments, yet these governments have chosen repeatedly to delegate executive, judicial and legislative powers and substantial discretion to supranational institutions such as the Commission, the Court of Justice, and the European Parliament. In The Engines of Integratio, the first full-length study of delegation in the European Union and international politics, Mark Pollack draws on principal-agent analyses of delegation, agency and agenda setting to analyze and explain the delegation of powers by governmental principals to supranational agents, and the role played by those agents in the process of European integration.