The costs of military ventures and concern for human rights has increased the importance of international sanctions in the twenty fist century, but our knowledge is still limited in this area. The United Nations sanctions on Libya, Al Qaeda and Rwanda, or the European Union restrictive measures on the US, Transnistria and Uzbekistan are sparsely covered by the media and attempts to measure the effectiveness of any of these sanctions comes up against the fundamental (unanswered) question: What can sanctions do and when? This book undertakes an innovative approach that overcomes these problems by enhancing our understanding of how sanctions work and by explaining what we can expect from their imposition. Through the analysis of the sanctioning experience of the United Nations and the European Union after the Cold War, the investigation tests a comprehensive theoretical model and concludes that the context in which sanctions are imposed is a crucial element in deciding the type of sanctions adopted. Giumelli shakes the pre-constituted conceptions that we have on sanctions and sets the terms for more constructive debates in the future.