This chapter addresses the cooperation of Europol and Eurojust with external partners in the fight against crime. Both agencies take part in the EU’s efforts to promote and strengthen cooperation in criminal matters with third countries and international organizations. The tools and expertise they have developed make them valuable partners with which to cooperate, and their external activities are essential to support cross-border investigations and prosecutions. The chapter discusses the recent revisions to the Regulations organizing the modalities of their cooperation with external partners. While the revisions mark a move towards greater harmonization, the two agencies face two challenges that may limit their external activities: (1) the diversity in their relations with external partners, and (2) the need to ensure an appropriate balance between efficient cooperation, data protection and protection of fundamental rights. On the latter, the chapter assesses potential strengths and gaps in the agencies’ political and judicial accountability.