This article provides a legal perspective on the new European External Action Service (EEAS), and positions this new body in the reshuffled institutional balance of EU external relations. Towards that end, the paper examines the EEAS’ legal nature as compared to that of Council, Commission, their support services and EU agencies, and seeks to define the EEAS’ sui generis status in the EU institutional set-up: What are the implications of its absence of legal personality, what does its ‘functional autonomy’ from the Council and Commission imply, what are its formal powers – if any, and could the EEAS be drawn into proceedings before the Court of Justice? In answering those questions, this article then examines to which extent the legal-institutional choices on the structure of the EU External Action Service reflects the age-old tension entrenched in EU external relations law: the EU’s nature as an internally diverse entity, which seeks to present a coherent Union voice to the world.