Comparative administrative law is emerging as a distinct field of inquiry after a period of neglect. To demonstrate this claim, the authors summarize their edited volume on the topic – a collection that aims to stimulate research across legal systems and scholarly disciplines. After a set of historical reflections, the authors consider key topics at the intersection of administrative and constitutional law, including the contested issue of administrative independence. Two further sections highlight tensions between expertise and accountability, drawing insights from economics and political science. The essay then considers the changing boundaries of the administrative state – both the public–private distinction and the links between domestic and transnational regulatory bodies, such as the European Union. The essay concludes with reflections on a core concern of administrative law: the way individuals and organizations across different systems test and challenge the legitimacy of public authority.