This paper explores the influence of the Lisbon Treaty on the EU’s position in the world as a global actor. In economic terms, the EU has been an influential actor. However, to be an influential global actor, the EU also needs to be strong in the fields of security and defence. The main goals of the Lisbon Treaty were to increase the efficiency of decision- making mechanisms following previous enlargements and to address new global challenges such as the fight against terrorism, climate change and energy security. The Lisbon Treaty introduced new positions such as the President of the Council and the High Representative for Foreign Affairs and Security Policy. The effectiveness of these positions, the relations between them, and their interaction with the President of the Commission and the leader of the member state holding the Presidency, will influence the position of the EU as a global actor. The Lisbon Treaty opened the way towards the future accession of Croatia, Turkey and Macedonia. The accession of Turkey would positively affect the position of the EU as a global actor in terms of energy politics and the fight against terrorism. Turkey is a transit country of important energy networks for Caspian, Middle Eastern and Russian oil and gas. In addition to her geostrategic importance and military capabilities, Turkey also has civilian contributions to make to the security of Europe, such as participation in EU peacekeeping operations. If the EU wants to have a more proactive foreign policy in different regions of the world, such as the Balkans and the Middle East, Turkey’s membership will be an asset.