This article examines the writings of Austrian parliamentarian, editorialist, and social theorist Otto Bauer concerning the Jews of western, eastern, and central Europe. Though Bauer has been seen as a champion of the concepts of national and cultural autonomy in general, there is considerable scholarly confusion as to his views on whether the Jews did or could constitute a nation. Reconstructing Bauer’s role as a Marxian theorist of nationalism in the historical context of the Habsburg Empire between the first Russian Revolution and World War I, I make a case for the multilayered sophistication of Bauer’s concern with the central- and eastern-European question of nationalities, its relation to class struggle, and the place of the Jews in the dynamics of both. Bauer’s analysis of the Jews as a nation without a state, his interest in a theory of Jewish cultural hybridity, and his concern with the precarity introduced with any scheme of state partition or redefinition are all specifically grounded in the unique circumstances of the late Habsburg Empire but came to be of much broader relevance to twentieth-century theorists because they speak to an age of universal vulnerability. Exploring the proposition that Bauer’s concept of national identity always incorporated reflections on the “negative,” exclusionary, and weaponized dimensions of identity and group belonging, I argue that Bauer’s unique analyses of antisemitism and its relation to caste and class economies offer rich resources for reinterpreting the role of Jews alongside the problem of antisemitism in European history.