This chapter studies the cooperation between the European Commission and competition authorities and courts outside the EU, at both bilateral and multilateral level, and highlights the importance of that cooperation in the context of proliferation of competition regimes and the continual increase in cross-border business activities. In more than half of its enforcement activities, the Commission cooperates with one or more foreign jurisdictions, obviously with varying degrees of intensity. The bulk of this international cooperation, in the fields of both merger control and anticompetitive practices, is with the U.S. and the Canadian competition authorities. The chapter then sets out the legal framework for international cooperation and explains the principles determining the Commission’s jurisdiction in cases having an international dimension. It also considers cooperation in antitrust enforcement, with particular attention given to the exchange of information and disclosure of evidence.