There is a glaring imbalance between the impressive amount of research into first-tier EU decision-making by the Council of Ministers and the European Parliament and the limited research into second-tier EU rule-making by the Commission and the comitology committees. This book seeks to redress that imbalance and find answers to fundamental unresolved questions about the comitology system. It looks at why the system was created, how it has evolved over time and how it functions day to day. The EU Comitology System in Theory and Practice applies a novel theoretical approach, the delegation perspective, and provides answers by analysing a plurality of data sources, including EU legislative databases, survey data of comitology committees, legal documents and news reports. The book argues that member states use the comitology system to strike a balance between delegating powers to the Commission and controlling it.