Police and judicial cooperation in criminal affairs have been considered as predominantly internal policies of the EU integration process. However, since the creation of the Area of Freedom, Security and Justice in 1999 the EU has consistently promoted cooperation with international institutions. Cooperation with international institutions in the fields of police and judicial cooperation in criminal matters has occurred either to assert the EU’s role as a global actor, or as an instrument to promote and advance internal integration. This chapter shows that in spite of formal obstacles that may hinder EU activism, participation and promotion to the activities of international institutions cover the adoption of norms, operational cooperation and the support of international institutions with third countries. It also argues that the various forms of engagement are explained by the specific need to preserving the uniformity of EU internal policies.