Introduction: 1. Informality in global governance: an introduction Kenneth W. Abbott and Thomas J. Biersteker; Part I. Informality of Institutions: 2. From complex interdependence to complex governance Miles Kahler; 3. Soft pooling: how IIGOs govern collective decision-making without delegation Duncan Snidal and Felicity Vabulas; 4. Informal governance in the development regime: a political economy perspective on two types of informal organizations Bernhard Reinsberg; 5. Informal governance of international climate policy Axel Michaelowa, Katharina Michaelowa and Chandreyee Namhata; 6. Why do states cooperate informally? Comparing secret agreements in Europe and the Middle East Barbara Koremenos and Melissa Carlson; Part II. Informality Within Institutions: 7. International consequences of domestic politics: how divided government drives informal US influence in the World Bank Erasmus Kersting and Christopher Kilby; 8. Knowledge guardians in informal networks: how international organizations retain knowledge of strategic errors Heidi Hardt; Part III. Informality Around Institutions: 9. The role of transnational policy networks in informal governance: creating the office of the ombudsperson at the United Nations Thomas J. Biersteker; Part IV. Normative Issues: 10. Can informal governance promote procedural justice? Lora Anne Viola; Conclusion: 11. Conclusions: a research agenda on informal global governance Kenneth W. Abbott and Thomas J. Biersteker.