Even though EU agencies are poorly embedded in the EU's constitutional framework their proliferation continues. If and when these agencies establish relations with international counterparts, they sometimes also conclude arrangements or agreement with those counterparts. This brings together two constitutionally problematic issues: the EU's external action and the limits to the empowerment of EU agencies. This article aims to identify the constitutional and positive law frameworks applying to EU agencies' external action, and looks at a number of examples. It is shown how the positive law framework does not properly reflect the requirements of EU constitutional law, resulting in legal ambiguity and accountability problems. Some EU agencies ...