Do international organizations (IOs) help states to solve coordination problems over policy choices? We analyze a formal model of coordinated adaptation in which states use costly signals to transmit information about their preferences. We show that states only delegate to IOs if states are sufficiently aligned and face little uncertainty about each other’s preferences. Although states gain from delegation by achieving more policy coordination, they also incur more costs because of inefficient signaling. States misrepresent their preferences to ensure that policies are coordinated on their own preferred outcome, and delegation to IOs makes states want to misrepresent their preferences more strongly. This effect can be so strong that the gains from international coordination are insufficient to warrant delegation to IOs. We discuss the robustness of our results to different types of IOs and provide implications for the design of institutions.