Understanding the impact of regime complexes on global governance calls for creative policy thinking. This introduction provides a new and more precise definition of the concept of regime complex. It also suggests specific tools to characterize regime complexes and analyze their impacts on global governance. The articles in this issue deepen the analytical understanding of complexes by examining concrete examples in various domains of global governance such as piracy, taxation, energy, food security, emissions reduction, carbon sinks, biosafety, and refugee governance. In addition to providing an in-depth description of a variety of different regime complexes, this issue is innovative on three accounts: (1) it presents complexes as both barriers and opportunities for global governance and gives explanations for these diverse outcomes; (2) it shows how a broad spectrum of actors is necessary for understanding the creation and evolution of complexes; and (3) it qualifies former claims to the effect that only powerful actors can impact regime complexes.
Keywords: regime complexes, networks, institutional centralization, institutional fragmentation, institutional density