Why do states go through the trouble of seeking authorization from multilateral institutions to use military force when they are not required to do so? How do states choose the international organization through which to work? Why do citizens sometimes demand a multilateral response to an international crisis, yet at other times seem content when their leaders act unilaterally? Terrence Chapman takes up these questions in his persuasive and important book Securing Approval. The answer, he says, is domestic politics. Using a game-theoretic approach supported by a wealth of empirical evidence, Chapman shows that international organizations (IOs) provide important information to domestic publics. This information can affect public opinion and, by extension, foreign policy. A short review does not do justice to this nuanced and smart book. Nevertheless, I will outline the author's central argument before discussing the book's contribution to the literature. I conclude by raising three issues that might serve as avenues for future research.