The international law angle is essential for assessing the external relations of European Union (EU) agencies on the international plane. The main yardsticks against which the international actions of the EU agencies should be assessed are the principle of institutional balance, as well as the doctrine of delegation of powers. This chapter shows that a broad view on the Union's external relations or action is taken, according to which the Union's external relations encompass the international activities performed in all EU policy areas from EU external policies to the external aspects of its internal policies. The Lisbon Treaty also attempted to make clearer the delineation between the Union's categories of competences. Beside the Commission, the European Central Bank and European Investment Bank are explicitly provided with certain international cooperation tasks by the Founding Treaties. The legal-analytical framework for assessing the EU agencies as global actors requires using the lens of both EU and international law.