The author is grateful to Adrienne Héritier and Julia Sievers for their detailed comments on earlier drafts. This paper also benefited from the thoughtful suggestions of Laurie Anderson, Armen Hakhverdian, Alexia Katsanidou, and Quinton Mayne. All errors are the author’s.Why do states occasionally select two di_erent mechanisms to govern decision-making in international organizations (IOs), one that provides for formal voting and another in which decisions are taken through consensus? Almost all IOs have official voting rules described in their charter, but many times these organizations take decisions and generate outcomes in the absence of a vote. In this paper, I investigate the origins of consensus-based voting and how consensus procedures may be viewed in the presence of the official, de jure, voting rule, especially when states know that a particular policy will not come to an official vote. I argue that because the outcomes of organizational decisions have distributional implications for states, that state-actors will bargain in “the shadow of the vote” and that the official voting rule plays an important role in the decision to include consensus procedures. I test these claims empirically using an original data set of voting rules for international organizations
