Adaptation to the adverse impacts of climate change is a rapidly developing area of policy and the subject of active negotiation at the international level under the UN Framework Convention on Climate Change (UNFCCC). This article applies theories of norm evolution to the adaptation negotiations. It proposes that the history of these negotiations can best be understood as a contest between two proposed framings that can be roughly characterized as “adaptation as development” and “adaptation as restitution.” These two framings have some similar and some contradictory implications for policy. The article shows that the major areas of consensus and controversy around adaptation in the UNFCCC negotiations map closely to these areas of similarity and contradiction, respectively. Though the “adaptation as restitution” norm is relatively disadvantaged on many measures of norm-fitness suggested by previous authors, it nevertheless appears to help explain the development of adaptation institutions both within and outside the UNFCCC. A hybridized norm that can be described roughly as “like development but different” is coming to characterize international adaptation institutions.