Do international organizations really do what their creators intend them to do? In the past century the number of international organizations (1Os) has increased exponentially, and we have a variety of vigorous theories to explain why they have been created. Most of these theories explain IO creation as a response to problems of incomplete information, transaction costs, and other barriers to Pareto efficiency and welfare improvement for their members. Research flowing from these theories, however, has paid little attention to how IOs actually behave after they are created. Closer scrutiny would reveal that many IOs stray from the efficiency goals these theories impute and that many IOs exercise power autonomously in ways unintended and unanticipated by states at their creation. Understanding how this is so requires a reconsideration of IOs and what they do. In this article we develop a constructivist approach rooted in sociological institutionalism to explain both the power of IOs and their propensity for dysfunctional, even pathological, behavior. Drawing on long-standing Weberian arguments about bureaucracy and sociological institutionalist approaches to organizational behavior, we argue that the rational-legal authority that IOs embody gives them power independent of the states that created them and channels that power in particular directions. Bureaucracies, by definition, make rules, but in so doing they also create social knowledge. They define shared international tasks (like "development"), create and define new categories of actors (like "refugee"), create new interests for actors (like "promoting human rights"), and transfer models of political organization around the world (like markets and democracy.) However, the same normative valuation on impersonal, generalized rules that defines bureaucracies and makes them powerful in We are grateful t
