Over the past decade developed states have committed significant public financing for climate change adaptation. Much of this public financing flows through international development organizations. States have delegated the implementation and monitoring of adaptation to existing international organizations such as the World Bank, the United Nations Development Programme, and the Organisation for Economic Cooperation and Development. Scholars have noted that states delegate discretion to specialized organizations to perform a task on their behalf, but have not explored how uncertainties about the nature of the task affect delegation. This article addresses this gap by distinguishing the concept of epistemic ambiguity (when states are uncertain about the exact nature of a task) from strategic ambiguity (when states do not reach consensus over a task due to political differences) in order to address the question: how have states and international organizations defined and implemented adaptation activities? The question is answered through case studies of: (l) adaptation projects administered by the United Nations Development Programme and the International Organization for Migration in Kenya; and (2) states’ and international organizations’ attempts to develop methodologies for reporting adaptation financing. The case studies are based on: primary documents published by states and international organizations, secondary literature on climate finance, and interviews with adaptation experts. This article argues that states have not precisely defined adaptation, and that this is substantially due to epistemic ambiguity. It then identifies two consequences of epistemic ambiguity: a proliferation of activities labelled as adaptation, and difficulties tracking and monitoring adaptation assistance.