The European Union Agency for Law Enforcement Cooperation (Europol) became operational in 1998. Europol has become the central entity for cooperation between law enforcement authorities in the European Union.This book demonstrates that Europol’s responsibility, autonomy, discretion, accountability and transparency evolved, but were, and still are, in harmony. Even though instances of apparent inharmony exist, they should be seen as moments that demonstrate Europol is held accountable and offers transparency over its actions. Nonetheless, specific shortcomings in its accountability and transparency framework exist. Despite persistent calls for a European FBI or a more operational Europol, this book concludes that Europol will continue its steady trajectory and continue supporting the Member States, without any actual coercive powers. Nevertheless, Europol will become ever more influential for national law enforcement authorities, while being held accountable and offering transparency. The suggestion that Europol will evolve into a European NSA, without being held accountable, is unfounded criticism not based on proper research.Wannes Bellaert is an academic researcher at the Department of Criminology, Criminal Law and Social Law at the Faculty of Law and Criminology at Ghent University. This book is based on his doctoral dissertation to obtain the title of Doctor of Laws at Ghent University.