Explores the efficiency and effectiveness of new modes of European governance that are not based on legislation and include private actors in policy formulation. Focusses on the emergence, functioning, and impact of these new modes of governance, which include the open method of co-ordination, voluntary accords, and regulatory fora. Héritier answers important theoretical and normative questions by identifying when and how new modes of governance become institutionalized, as well as specifying conditions under which new modes of governance offer improved policy performance. The general aim of the chapter is to raise the various issues regarding the new modes of governance, and the general question is posed as to why these new modes have become more popular among policy makers, arguing that this is because the new modes are putatively considered to have greater political capacity and policy effectiveness. Based on political transaction cost theory, principal-agent theory, and political science policy analysis, claims are developed regarding the political institutional capacity as well as the instrumental policy effectiveness of the new modes of governance in different policy areas; these general claims are then explored against the background of four empirical cases in different policy areas, and the general insights gained are used to modify and refine the original claims. © European Union Studies Association 2003. All rights reserved.