The Frankfurt School did not devote sustained attention to antisemitism in the 1920s or for much of the 1930s. During the course of World War Two, however, the key theorists of the Frankfurt School dedicated themselves to developing a multi-faceted approach to the study of antisemitism. In the post-Holocaust era, moreover, Horkheimer and Adorno, while focusing on other matters, expressed ongoing concern about the continuing existence of antisemitism. This talk will analyse the reasons for the marked differences in the School’s attitudes towards antisemitism in three distinct periods, and the significance of these differences.