This chapter compares the normative justifications that global governance institutions (GGIs) provide in their public statements in order to legitimate themselves and through which they give reasons for their right to rule. Drawing on a comprehensive content analysis of annual reports published by nine GGIs between 1985 and 2017, the chapter analyzes the normative underpinnings of legitimation regarding the core purpose, procedures, and performance of GGIs. Moreover, it explores whether these justifications have been subject to change. The chapter shows that the main purpose that GGIs communicated has stayed remarkably stable over time. It emphasizes the central, but at times overlooked, role of legality in purpose-based normative justifications. Justifications concerning GGI procedures and performance, in turn, were more amenable to change. The chapter demonstrates that economic and regional GGIs more frequently relied on technocratic norms, while multistakeholder institutions were more likely to refer to democratic norms. In the case of GGIs with a comparatively high level of authority, such self-legitimation invoking democratic norms increased following periods of contestation of the institution’s authority. Such an increase, however, was typically only temporary.