As a prelude to the three themes in the volume, this chapter explores more generally the turn towards legitimacy in global governance research. The chapter suggests that this turn is partly explained by shortcomings in normative research on global democracy, and the potential of research on legitimacy to overcome those problems. The chapter discusses the merits and demerits of alternative conceptualizations of legitimacy in serving these purposes. The chapter concludes in favor of a normative-sociological understanding of legitimacy that is sensitive to beliefs among members of relevant audiences about the normative qualities of political institutions that are ultimately specified by analysts.