Essays on the political, legal, and philosophical dimensions of political legitimacy. Scholars, journalists, and politicians today worry that the world’s democracies are facing a crisis of legitimacy. Although there are key challenges facing democracy—including concerns about electoral interference, adherence to the rule of law, and the freedom of the press—it is not clear that these difficulties threaten political legitimacy. Such ambiguity derives in part from the contested nature of the concept of legitimacy, and from disagreements over how to measure it. This volume reflects the cutting edge of responses to these perennial questions, drawing, in the distinctive NOMOS fashion, from political science, philosophy, and law. Contributors address fundamental philosophical questions such as the nature of public reasons of authority, as well as urgent concerns about contemporary democracy, including whether “animus” matters for the legitimacy of President Trump’s travel ban, barring entry for nationals from six Muslim-majority nations, and the effect of fundamental transitions within the moral economy, such as the decline of labor unions. Featuring twelve essays from leading scholars, Political Legitimacy is an important and timely addition to the NOMOS series.