This chapter explores the broad contours of concepts of diaspora in modern Jewish thought. Philosophers, intellectuals, religious thinkers, and non-Zionist nationalists who disagreed on the ideal political structure for Jewish collective life (including Moses Mendelssohn, Hermann Cohen, Franz Rosenzweig, Simon Dubnow, Hannah Arendt, Mordecai Kaplan, and Horace Kallen) shared a commitment to diaspora as a value, rather than just a fact, of modern Jewish life. Yet the emergence of the terminology of diaspora in tandem with the rise of nationalism and Zionism shaped the theoretical evolution of diaspora as the binary opposite to homeland and statist visions of Jewish identity. As a result, seminal Zionist theorists deeply critical of diaspora life, such as Theodor Herzl, Achad Ha’am, and David Ben-Gurion, also had a key role in framing the significance of diaspora. Modern theories of diaspora internalized and contested the privileged position of territory and sovereignty demanded by the rise of nationalism in the late nineteenth and early twentieth centuries.