The creation of the European External Action Service (EEAS), the EU’s new diplomatic body, was accompanied by high expectations for improving the way Europe would deal with foreign policy. However, observers of its first years of operation have come to the opposite conclusion. This book explains why the EEAS, despite being hailed as a milestone in integration in Europe’s foreign policy, has fallen short of the mark. It does so by enlisting American institutionalist approaches to European questions of institutional creation, bureaucratic organisations and change. The book examines the peculiar shape the EEAS’s organisation has taken, what political factors determined that shape and design and how it has operated. Finally, it looks at the autonomous operation of the EEAS from a bureaucratic theory perspective, concluding that this is the best way to understand its course. Including data gathered from elite interviews of politicians and senior officials involved in the institutional process, an assessment of official documentary evidence and a survey of EEAS officials at the organisation’s beginning, it sheds new light on a controversial tool in the EU's foreign policy. This text will be of key interest to scholars and students of European Union foreign policy, public administration, and more broadly to European Union and European politics, as well as to practitioners within those fields.