This book for the first time addresses accountability in truly multi-level terms. It looks at accountability foreseen in the constitutional setup of the comitology system, as well as at how this plays out in practice at the European level and within national governments. Controlling Comitology combines findings from different levels of government, and analyses a plurality of data sources including interviews, survey data of committee participants and their superiors, legislative databases and meeting documents. The book argues that accountability has steadily improved over time, but also that unexpected gaps have emerged. This books is important reading for student and scholars of comitology as well as accountability and law-making in the European Union.