Politicians who downplay human rights violations committed under past dictatorships have gone on to win presidential elections in Argentina and Chile. How do voters respond to such denialist rhetoric, and why? I argue voters punish denialism only when they perceive it as anti-democratic and place a high value on democracy understood to include human rights. Using survey experiments, I find centrists in both countries punish denialist candidates because they view them as anti-democratic. Right-wing voters diverge: contrary to the expectation that they would excuse their own side, Argentine right-wing voters punish denialism; in Chile they do not. I trace this divergence to differing trajectories of collective memory: a pro-human-rights memory of the dictatorship became politically dominant in Argentina, while in Chile memory remains contested along ideological lines. I document these distinct trajectories through case studies and show through focus groups with right-wing voters how they differently interpret denialism and democracy.