Do international institutions contribute to peace-building? It could be doubtful, so much criticism is evoked: shortcomings, shortcomings and the interests of the most powerful states. Diplomates, academics and practitioners of these institutions are more nuanced. From a realistic and constructive perspective, they highlight the strengths and weaknesses of what international actors have created and do not want to abandon. At the end of their investigations, it appears that, while it is still possible to war against the opinions of international institutions, it is now difficult to avoid them in order to pay. The choice of issues dealt with — collective security, disarmament, mediation, peace-building, human security, poverty and inequality reduction, international criminal justice and multilateralism — makes this book a reference to international institutions. [Editor summary]