This article introduces a special issue of West European Politics on the COVID-19 crisis. It first sets out the dual challenge to democratic principles and democratic performance that the COVID-19 pandemic has posed to European liberal democracies. Three bodies of scholarship are especially relevant in framing this dual democratic challenge: those that provide accounts of policy, institutional and legitimacy crises; accounts of the governance of emergencies and of emergency politics; and accounts of political turbulence and organisational and policy responses. The articles that comprise the special issue provide comparative empirical insights into first reactions, with a focus on the responses by political decision-makers, European publics and the EU. Assessments of the likely longer-term, potentially transformative effects of COVID-19 on the principles and performance of European liberal democracies will need to draw on both sectoral and systemic perspectives, with a focus on the organisation and operation of public authority and the state.