The emergence and expansion of European Union (EU) agencies are considered by some as one of the most significant developments in the institutional structure of the EU. The origins of the 'agency model' are not very recent, the first two European Community agencies having already been established in the 1970s. The European agencies are increasingly interacting in various ways with actors outside the EU and they are becoming increasingly visible actors on the international arena. The agencies' potential to engage in some sort of international relations seems to be supported by their own legal framework, as well as by their current practice. This chapter explores the role of the European agencies in EU external relations and on the international plane. More specifically, it scrutinises the international cooperation mandate, the tasks and instruments entrusted to EU agencies, together with their legal status as actors with an international dimension. It also presents an overview of the key concepts discuss in this book.