With the start of the first prosecutions by the International Criminal Court and the closing phases of the work of the ad hoc Tribunals, this is a good time for a new book on international criminal law and its institutions. This book is intended as an accessible yet challenging explanation and appraisal of international criminal law and procedure for students, academics and practitioners. We focus on the crimes which are within the jurisdiction of international courts or tribunals – genocide, crimes against humanity, war crimes and aggression – and the means of prosecuting them. We also briefly discuss terrorist offences, torture, and other crimes which are not (yet) within the jurisdiction of an international court or tribunal.