This introduction presents the theoretical framework, aims, and summary of this special issue. We want to explain the European Union’s (EU) response to the COVID crisis from a ‘polity perspective’ (Kriesi 2021; Ferrera 2005). We conceptualize the EU as a compound ‘experimental’ polity which develops along three dimensions: binding (capacity building and sovereignty), bounding (bordering), and bonding (solidarity and loyalty). We structure the contributions around the following themes:polity building and polity maintenance(how did COVID affect policymaking in the EU?);reactions to polity building: public support, populism, and emergency politics(did the European public perceive emergency politics as illegitimate? did the EU’s policy response spur populism?); andsolidarity and bonding(to what extent did the crisis stimulate cross-national solidarity?). We show that, overall, the EU weathered the COVID storm better than expected for a potentially fragile multilevel polity. The crisis triggered unprecedented institutional innovation, underpinned by pan-European solidarity, and EU citizens did not backlash against emergency politics.