This introduction to the special section explores the nexus between global health governance and international health diplomacy. In these dynamic governance spaces, particular attention is paid to the multi-level and multi-actor character of global health governance and how health diplomacy functions in such a complex context. It is pointed out that the regional level plays both vertical (i.e., as an intermediary between the global and national levels) and horizontal (i.e., interregional) roles. The contributions to the special section develop the conceptual understanding of those interactions and analyze a number of concrete cases, including the African Union, ASEAN, the European Union, SADC, and UNASUR.