This study uses the case of Holocaust Day in Israel to examine the premise that national days impact national identity and collective memory. Specifically, the study examines whether a very unique type of national day-Holocaust Day-impacts national identification, nationalism, and collective memory in the form of Israeli Jews' perceptions of the "lessons" of the Holocaust. This study uses panel survey design data on national identity and perceptions of the Holocaust's lessons from the same sample of Israeli Jews (N = 665) collected two months prior to Holocaust Day and again during and after Holocaust Day. During and after Holocaust Day, respondents expressed increased levels of nationalism and more perceptions of both particularistic and universalistic Holocaust lessons. Participation in Holocaust Day practices had a stronger relationship with nationalism and national identification during Holocaust Day than before but a weaker relationship with the perception of a universalistic lesson during Holocaust Day. These findings indicate that Holocaust Day impacts national identity and collective memory and highlights the multifaceted nature of the relationships between national identity, collective memory, and national days. The theoretical implication of the findings as well as the case comparability are discussed in light of the findings.