The EU has a broad and complex network of external relations, developed both within the context of the European Community (trade relations, development cooperation, etc.) as well as within the framework of the common foreign and security policy. This chapter first details how the Maastricht Treaty laid out the famous three pillars which originally made up the EU. The Lisbon Treaty would ultimately remove this three-tiered structure, thereby affirming the EU's singular and unified legal personality, both domestically and internationally. The EU enjoys important competences in different fields of its external relations. As shown next in this chapter, these competences can be distinguished as being either explicitly or implicitly conferred, as well as exclusive or shared with regard to the member states. The Union's competences include inter alia the conclusion of international agreements. To a large extent, the Lisbon Treaty has, along the lines subsequently described, unified the procedures behind the conclusion of such international agreements, while also awarding an ever-increasing role to the European Parliament. The EU also participates to varying degrees in many international organisations. As outlined, such participation is mostly a joint venture with the member states. This implies a necessarily close cooperation between the Union and the member states when acting within these international institutions. In conclusion, the chapter highlights the clear intent on strengthening the coherence between the different fields of the EU's external action, as well as between its internal and external policies. Coherence remains a difficult goal, even though the Lisbon Treaty improves the overall situation through important institutional reforms.