Abstract: Between 1990 and 2018 Chile experienced one of Latin America’s most dramatic declines in party identification, from 80% in the early 1990s to under 20% in 2016. This decline seems puzzling given a highly institutionalized and programmatic party system, and low levels of ideological convergence. This paper argues that, to a large extent, the decrease in partisanship can be understood as a consequence of the erosion of the main political cleavage that articulated the political landscape throughout this period: the dissolution of the conflict between the supporters of the previous military regime (1973-1990) and the advocates of democracy. Because this conflict was the key driver of political identities following the dictatorship, as it faded over time, particularly after conservative parties distanced themselves from the military regime for electoral reasons, partisans lost an important reason to feel attached to political parties. More broadly, the paper argues that unless political identities are continually reinforced by political actors, they are unlikely to remain stable sources of identification.