Since its early beginnings, the member states of the European Communities have tried to establish a common foreign policy and at the same time were reluctant to implement it. Only the Maastricht Treaty introduced an institutional framework. However, the emerging Common Foreign and Security Policy (CFSP) has been criticized for its lack of democratic legitimacy, since it has been dominated by the member states at the expense of democratic control by the European Parliament (EP). Therefore, it is puzzling that the Lisbon Treaty implemented new powers for the EP in external relations. Why was the Parliament given these new powers? Is it connected to the ‘democratic deficit’ of foreign relations and therefore a new strategy of the European Union (EU) to enhance legitimacy or is this process a result of inter-institutional dynamics? Are these mechanisms relevant for the integration process in general? Derived from New Institutionalism, this paper argues that the European Parliament was granted new powers due to its strong democratic profile as well as inter-institutional dynamics within the political system of the European Union. The case study on the new European External Action Service (EEAS) focuses on the consequences of the new provisions of the Treaty. Content analyses of inter-institutional documents on the construction of the EEAS suggest that the increasing recognition of the Parliament as an important policy actor by the other European institutions translated into institutional powers to an even greater extent than intended in the Lisbon Treaty. Hence, the results have important implications for institutional as well as democratization analysis of the EU and International Organizations in general.