This lecture will provide an overview of my dissertation project, which re-examines republicanism as one of the key political-theoretical foundations of radical democratic thought in the late Habsburg Empire and its successor states, a space I call “Danubian Europe.” Republicanism is not particularly visible as a tradition of political thought in this part of Europe, largely because it was overshadowed by the repeated coming-to-power of more hegemonic ideologies (e.g., liberalism, nationalism, socialism, and fascism) through the long nineteenth century, the short twentieth, and in our own day. As such, republicanism was neither politically realized, theorized as a standalone ideology, nor given extensive historiographic treatment as in Western Europe and North America. Thus, as one of the more complex and interesting modern cross-ideological frameworks of political thought produced in Danubian Europe, republicanism deserves intellectual and historiographic canonization on regional and comparative bases. In order to make modern republican political thought visible in this part of Europe, then, I have chosen to examine the place of republicanism on the Left, where it found its most clearly pronounced and complex articulations. Between 1900–48 in Danubian Europe, this “movement of negation toward the existing world”—as Polish philosopher and intellectual historian Leszek Kołakowski defined “the Left” in 1968—was largely represented by civic radicals, anarchists, left-liberals, radical peasantists, social democrats, socialists, and communists, all of whom consistently claimed the ideals of the French Revolution as their own from the late eighteenth century onward. This project aims to integrate twentieth-century developments in republican thought in Danubian Europe into existent historiographic investigations about republicanism as a shared European—that is, a truly pan-continental—intellectual tradition, while still placing central emphasis on specific regional dynamics and autonomous paths of development.