Intergovernmental organisations (IGOs) are entities created by states to facilitate cooperation, provide a forum for discussion, resolve disputes, and exchange information among nations. The United Nations (UN) is a prominent global intergovernmental organisation. The UN system has been working on the climate change adaptation (CCA) agenda through different mechanisms. This chapter begins with a description of the context in which IGOs operate by addressing the topics of international disaster risk reduction (DRR) and climate regimes, the power balance within the international mechanisms, the common but differentiated responsibility, and the quest for flexible regimes. It addresses the DRR and climate change cases. The chapter deals with an inside analysis of the UN, the mandate, and the challenge of moving the system in one direction. UN organisations have increased their accountability by adopting a single set of indicators to measure progress as they accelerate and mainstream disaster risk reduction into their operations.