The Treaty on the European Union stipulates that one of the key objectives of the Union is to provide citizens with a high level of safety within an Area of Freedom, Security and Justice. Given that the fight against terrorism is a prominent aspect of this general objective, it is remarkable that, in spite of its political relevance and decade-long history, it has only relatively recently received due attention in the academic community. Yet an analysis of the successes and failures of the EU's involvement in this field is imperative and this is a particularly pertinent moment to take stock of progress. The goal of this book is therefore to look back at the post-9/11 period and answer the question of whether, when it comes to the measures taken to combat terrorism following these attacks, the EU has lived up to the promise made in its founding treaties. In pursuing this goal, this volume presents the views of leading experts casting a critical eye over the EU's performance, recognising achievements but also being suitably critical when the realities did not match the European rhetoric. In doing this, the book makes a significant contribution not only to the scholarly investigation of European Union policies, but also to the study of counter-terrorism in general. This book was published as a special issue of Intelligence and National Security.