The history of depoliticisation in modern Europe is both much longer and more multifaceted than recognised in much recent scholarship, which often conflates depoliticisation with neoliberalism. Ever since the emergence of modern politics as a distinct sphere in the late eighteenth century, the politics of depoliticisation has involved two dimensions at once: one of competition over resources of various kinds, the other of conflicts about the definition of the political sphere itself. Engaging with research from political science, history, and other disciplines, this introductory chapter outlines the volume’s approach to depoliticisation as a form of boundary work: the deployment of various discursive, performative, and institutional strategies to redefine the boundaries between the political and its perceived alternatives. In modern European history, a great variety of actors has attempted to ensure that some entities, groups, or issues were cleared of their political character, which, paradoxically, could only be achieved through political engagement with the nature and limits of politics itself. The introduction concludes by drawing together key insights from the volume’s chapters, highlighting five contextual factors most relevant to the historical analysis of depoliticisation in modern Europe: regime types, communicative configurations, critical junctures, value systems, and collective action repertoires.