A rapidly growing sociological literature demonstrates that many policies of modern states, such as educational expansion, environmental protection, and human rights, are shaped by embeddedness in the world polity. The world polity is conceptualized as a network of international organizations and states, and yet the structure of this network is rarely examined. This relative inattention to the social structure of the world polity is surprising, given that world polity theory implies that the world polity should be an increasingly dense and even field of association. This paper explores essential structural implications of world polity theory using a formal network analysis of the population of intergovernmental organizations since 1820. Using the language of network analysis, the world polity is a two-mode network: States are interlinked through memberships in organizations, and organizations are interlinked through their member states. Accounting for this bimodality reveals growing fragmentation in the world polity driven by intergovernmental organizations that have become less densely connected by common member states, increasingly centralized around a few prominent organizations, and increasingly unequal in structural position. This fragmentation reflects, in part, a recent increase in the regionalization of the world polity.