The past decade has witnessed a proliferation of regulatory agencies at both the national and the EU level. This coherent and clearly structured book is the first of its kind to analyse in equal measure, and interdependently, both national regulatory authorities and European agencies. It brings together a select group of highly esteemed contributors - authorities in their fields - to provide a systematic and over-arching view of regulation in the EU. Unlike many of the previous attempts to shed light on this increasingly opaque and complex co-existence of regulatory systems, this book takes a genuinely multi-disciplinary approach with integrated perspectives from law, politics and economics. Exploring firstly the rationales for the existence of agencies, the book then goes on to examine how agencies are designed in the EU before considering the legal and political challenges they raise, and finally comparing them with international agencies and agencies in an enlarged Europe and the wider world. Academic researchers in the fields of law, economics and politics will find Regulation through Agencies in the EU of great interest as will EU law practitioners, policymakers and regulators in Europe.