The proliferation of international rules, laws, and institutional forms raises important questions for regime theory. Looking at the theoretical and empirical arguments presented by all the contributors, however, it seems clear that that complexity's effects on actor strategies- particularly powerful actors- remain open to debate. Some of the posited effects of international regime complexity have contradictory or cross-cutting effects. Further effects of regime complexity- cross-institutional strategizing, the asymmetrical distribution of legal and technical expertise, and the fragmentation of reputation- can erode the significance of institutions in complex environments. This contribution considers the effect that regime complexity has on how powerful actors approach world politics- in part by connecting the current debate with past discussions about the significance of international regimes in world politics. © 2009 Copyright American Political Science Association.