International organizations are a growing presence in the global system but remain a neglected subject of study. This book by two prominent political scientists provides a groundbreaking look at their impact, making clear that international organizations may be created by powerful states but, once established, are neither straightforward tools of states nor unalloyed servants of a global common good. In order to account for what international organizations do, it is first necessary to understand what they are: sprawling bureaucracies with their own distinct interests, rules, culture, and logics of action. Detailed case studies of the International Monetary Fund, the office of the UN High Commissioner for Refugees, and the UN Secretariat illustrate the various ways that international organizations exercise authority. Barnett and Finnemore conclude that the impact of these organizations lies less in the expert knowledge they wield than in the ways they define problems, set agendas, and deploy "intellectual technologies." The most intriguing insights of the book, however, emerge as the authors grapple with what the growing "global bureaucratization" means for democratic accountability.