This article introduces a special issue on the expanding research agenda on institutional fragmentation. The term refers to the growing diversity and challenges to coordination among private and public norms, treaties, and organizations that address a given issue area of international politics. International relations scholars increasingly address this phenomenon, framing it with alternative concepts like regime complexes or polycentricity. A considerable part of the existing debate remains focused on whether a centralized or polycentric governance architecture is preferable. Instead, as this special issue shows, domains of global environmental governance—like climate change, biological diversity, renewable energy, and forestry—are already fragmented. It is time to address new, more pertinent questions and help advance institutionalist research on this phenomenon. We introduce four major research themes for analyzing the fragmentation of different domains of global environmental governance: taking stock, causes, consequences, and responses.
* We would like to thank two anonymous reviewers for their comments. This special issue builds on an international workshop organized by the German Development Institute / Deutsches Institut für Entwicklungspolitik (DIE), together with the Environmental Change Institute (ECI) of the University of Oxford, in Bonn, Germany, August 29–30, 2011. We would like to thank the COST Action IS0802 (Transformation of Global Environmental Governance) for their financial support of the workshop, and the participants for their valuable contributions. Lastly, we would like to thank the editors of Global Environmental Politics, Kate O'Neill and Stacy D. VanDeveer, and managing editor Susan Altman, for their great support and excellent guidance.