Differentiated cooperation as the mode of governance in EU foreign policy

While the standard conceptualization of differentiation in the European Union (EU) focuses on differentiated integration, scholars devote less attention to differentiated cooperation. This article argues, on the contrary, that member states' engagement in differentiated efforts in EU foreign policy manifest themselves both in the form of differentiated integration and cooperation. It elaborates an original conceptual framework for exploring differentiated cooperation as a mode of governance. Drawing on the articles in this special issue, this introduction maps empirical manifestations of differentiated cooperation in various areas and dimensions of EU foreign policy. The results of the special issue show that differentiated cooperation has mostly manifested itself in informal patterns of cooperation, with the treaty-based mechanisms being limited. As such, the special issue reflects the differentiation and informalization processes occurring not only in the EU, but also in global governance more broadly.