Traditionally, much of the focus of the study of politics has been on formal arrangements and formal institutions. In recent years, however, this dominant focus has given way to an increasing concern with informal aspects of politics. This can be said for both the study of comparative politics and international relations more generally and for research on governance within the European Union in particular. Against this background, the aim of this research note is, first, to review the findings of research on informal governance and, second, to explore whether analytical concepts can be applied to the EU, with the aim of bringing greater conceptual clarity to the field and identifying future research agendas in this area. In a final section, the article also addresses the normative dimension of informal governance in the EU, discussing both the benefits and the risks of such arrangements from the perspective of transparency, efficiency and democratic accountability.