How can international organizations persuade governments to adopt policy recommendations that are based on private information when their interests conflict? We develop a game-theoretic model of persuasion that applies regardless of regime type and does not rely on the existence of domestic constituency constraints+ In the model, an international organization~IO! and a domestic expert have private information about a crisis, but their preferences diverge from those of the government, which must choose whether to delegate decision making to the expert+ Persuasion can take place if the international institution is able to send a credible signal+ We find that this can take place only if the preferences of the IO and the domestic expert diverge and the institution holds the more moderate policy position+ This result contrasts with conventional wisdom, which holds that the necessary condition for IOs to exert influence is support from a domestic constituency with aligned preferences+ Our model suggests that, far from being an obstacle to international cooperation, polarized domestic politics may be a necessary condition for IOs to exert effective influence+ International organizations~IOs! have been tasked with providing early warnings on a wide range of issues, but state leaders and informed publics have become increasingly skeptical about their policy advice+ There are inherent conflicts of interest between IOs and their individual member states, and the legitimacy of important IOs is subject to persistent challenges+ The effectiveness of international institutions as policy advisors depends on trust+ Under what conditions can an international institution credibly convey information to a government that does not share its preferences?Consider three examples+ In 2007, the Intergovernmental Panel on Climate Change~IPCC! issued its Fourth Assessment Report, which summarized recent research indicating that global climate change was progressing more rapidly than previously believed and called for dramatic reductions in carbon emissions+ It has no power to enforce these recommendations+ In 2003, the World Health OrganizaWe thank