Legitimacy is an important source of power for authorities because it enables them to gain voluntary deference from their followers. For this reason, social psychologists have long sought to understand why people imbue authorities with legitimacy (French and Raven, 1959). Whereas the effects of procedural justice on perceptions of legitimacy in organizations and societies are already well established (Lind & Tyler, 1988; Tyler, 2006), this paper describes four studies that demonstrate the existence of a second, distinct, motivation underlying legitimacy - the motivation to justify existing authority relations (Jost & Banaji, 1994). Two cross-sectional studies and two panel-studies, conducted in real-world settings, were used to demonstrate this justification effect, which goes beyond the traditionally found impact of procedural justice. We predicted that a motivation to justify authorities would emerge in contexts where people depend upon these authorities for the provision of desired resources. All four studies found distinct effects of dependency on legitimacy, beyond those of procedural justice. Dependency on an authority affected legitimacy perceptions in terms of increased trust and confidence in the authority, empowerment of the authority, and deference to the authority. These findings suggest that both the justice motive and the motivation to justify determine the perceived legitimacy of an authority. In other words, perceptions of legitimacy increase not only when authorities exercise fair procedures, but also when subordinates depend on these authorities. The latter effect opens up the disturbing possibility that people will legitimize procedurally unjust leaders, highlighting the complicity of subjects in their own subordination.