This essay examines Isaiah Berlin's ambivalent relationship with the ideas and practices of Jewish nationalism and the ways in which this ambivalence shaped some of the key premises of his political thought. Drawing upon extensive archival research in his unpublished letters from the mid-1930s to the late 1950s, this essay reconstructs Berlin's attempt to reconcile himself with the national idea. This attempt forced him to enrich his liberalism, and pushed him to develop “Diaspora Zionism” and adopt the Jewish normalization discourse. In the course of those intra-Jewish debates Berlin also began to conceptualize freedom as an opportunity concept, an idea that would later become central both in Berlin's famous negative concept of freedom and in his pluralism. Adopting a dual perspective, which considers Berlin as both a British liberal and a Russian-Jewish émigré intellectual, I therefore offer to see the Jewish Zionist writings as complementary rather than secondary to Berlin's “liberal” enterprise.