While the major feature defining United States’ (US) foreign policy since the Cold War has been the use of coercive means such as military power and economic sanctions, the European Union (EU) international role, despite recent attempts to develop military capabilities, remains that of a civilian power. The literature on transatlantic relations has explained this difference by stressing the different positions of the two actors in the international balance of power and pointing at their divergent value and normative frameworks. This article, by comparing the EU and US policy-making processes, introduces a further explanation. It argues that, although the two polities share the features of Compound Democracies, the different institutional organization of their foreign policy-making processes has generated powerful incentives for pursuing different kinds of international action.