Scholars warn that affective polarization – the tendency of partisans to dislike or even loathe supporters of opposing political parties – undermines citizens’ commitments to principles and norms on which democracies are founded (i.e., democratic support). Within the academic literature, speculation about the potential political consequences of affective polarization on democratic support is rife, but empirical evidence is inconsistent and mixed at best. In this project, I aim to address this gap by comprehensively studying the extent to which affective polarization erodes citizens’ democratic support in Europe. This project translates the concerns about the political consequences of affective polarization into a theoretical and empirical research agenda by (1) studying how affective polarization and democratic support relate to each other across countries and electoral contexts, (2) developing and testing a causal mechanism between affective polarization and democratic support, and by (3) examining the conditionality of the consequences of affective polarization on the losers and winners of salient political decisions. Methodologically, I employ cross-national survey data as well as survey experiments. This project offers innovative theoretical and empirical insights into a pressing question in contemporary scholarly discourse: To what extent does affective polarization threaten the quality and stability of democracies?