The principal-agent model holds great promise for understanding the institutional complexities of the EU and for moving beyond the sterile debate between intergovernmentalism and neofunctionalism. As yet, however, scholars have failed to exploit the insights that this construct affords. After a brief discussion of the principal-agent model, this article offers a critical examination of the way that the principal-agent approach has been deployed by liberal intergovernmentalism, institutional intergovernmentalism, historical institutionalist supranationalism, and rational-choice supranationalism. It argues that, in all four cases, the a priori commitments of the theorists, in support either of the view that the member states effectively control their supranational agents and dominate EU governance or of the belief in an inevitable trend towards greater integration, led by supranational institutions, prevent them from making the most effective use of the model. It proposes alternative applications that may prove more fruitful.