The definition of organized crime has long been the object of a lively debate, at national and international level. However, the discussions and analysis haven't yet led to one definitive answer to the question of what exactly does 'organized crime' mean. This book starts from the (rather obvious) assumption that many instruments adopted both at international and at national level set forth special legal regimes designed to target criminal groups featuring a stable organization - which are perceived as particularly dangerous to society. Therefore, identifying the notion of organized crime is crucial to establishing the scope of any legal instrument specifically designed for combating it. The aim of the book is to reassess the scope, the effectiveness and the overall coherence of existing legal definitions of organized crime, and to identify any need for a reconsideration of these definitions, specifically with reference to the EU legal order. It will be of interest to academics, practitioners and legislators working in the sphere of EU criminal law.