Compensatory Layering and the Birth of the Multipurpose Multilateral IGO in the Americas

International organizations come in many shapes and sizes. Within this institutional gamut, the multipurpose multilateral intergovernmental organization (MMIGO) plays a central role. This institutional form is often traced to the creation of the League of Nations, but in fact the first MMIGO emerged in the Western Hemisphere at the close of the nineteenth century. Originally modeled on a single-issue European public international union, the Commercial Bureau of the American Republics evolved into the multipurpose, multilateral Pan American Union (PAU). Contrary to prominent explanations of institutional genesis, the PAU's design did not result from functional needs nor from the blueprints of a hegemonic power. Advancing a recent synthesis between historical and rational institutionalism, we argue that the first MMIGO arose through a process of compensatory layering: a mechanism whereby a sequence of bargains over control and scope leads to gradual but transformative institutional change. We expect compensatory layering to occur when an organization is focal, power asymmetries among members of that organization are large, and preferences over institutional design diverge. Our empirical and theoretical contributions demonstrate the value a more global international relations (IR) perspective can bring to the study of institutional design. international relations (IR) scholars have long noted that international organizations provide smaller states with voice opportunities; our account suggests those spaces may be of smaller states’ own making.