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.