The European Union’s (EU) commitment to multilateralism is enshrined in Article 21(1) of the Treaty on the European Union (TEU), which proclaims that the EU “shall promote multilateral solutions to common problems”. It is also reflected in numerous documents and treaties produced within the framework of EU external relations (Council of the European Union 2003; European Commission 2006 and 2014). This commitment might seem natural, the EU being a multilateral organization itself. However, this intuition that the EU – as an internally multilateral actor – should also display more commitment to multilateralism externally appears problematic. This chapter examines the articulation between this internal and external multilateralism of the EU in the case-law of the Court of Justice of the EU (CJEU). It asks the question whether the main tool of legal interpretation deployed by the Court – teleological interpretation – is inherently biased towards the internal or external perspective.