This introduction questions the idea of a “crisis” of multilateralism. It first recalls that the historical advancement of multilateralism and the steady empowerment of international organizations have always been accompanied by simultaneous destabilizing crises, from the League of Nations inability to prevent World War II up to the United Nations’ long paralysis during the Cold War. Multilateralism does not seem to be in a better shape today after the assaults of President Trump against its core values and institutions, the “sanitary sovereignty” displayed by States in the wake of the Covid-19 pandemic, and the failure of the UN in the “management” of deadly armed conflicts such as the war in Syria and the war in Ukraine. However, the purpose of this book is threefold: to deconstruct the diagnosis of a “crisis” of multilateralism, to consider the concept of “crisis” as a matrix of multilateralism historical dynamic, and to demonstrate the current resilience of multilateralism.