Scholars of judicial politics are currently engage in a debate over whether and to what extent ideological dissatisfaction leads the public to have diminished perceptions of the Supreme Court's legitimacy. In this dissertation, I contribute to this debate by demonstrating in two novel contexts that ideological dissatisfaction does predict diminished views of the Court's legitimacy. Specifically, I use President Roosevelt's 1937 Court packing plan as a case study in which I show that support for New Deal policies strongly predicts supporting the Court packing plan. In another context, I show that support for specific institutional changes to the Court are best predicted by ideological distance from the Court. Finally, to explain why individuals come to view the Court as less legitimate when they are ideologically dissatisfied with the Court's decisions, I offer a new theory of judicial legitimacy using the social psychology concepts of motivated reasoning and cognitive dissonance.