This study examines the evolution of Jewish identity in modern times as a result of the onset of national and post-national sentiment both in Israel and the Diaspora. Its methodology comprises a comprehensive review of secondary sources and the use of extensive interviews as primary source material. It first analyzes the rise of nationalism in modern European society, which in turn led to the advent of a Jewish national identity in Europe culminating in the Zionist movement and the establishment of the State of Israel. It then reviews the origins of post-Zionist ideology from within the Zionist movement itself: the almost immediate development within the Jewish community in Palestine (later Israel) of an intrinsic Hebrew-Israeli identity disassociated from Diaspora Jewry, and the emergence of early critics and pragmatists who effectively served as precursors to, and are seen as inspirational role models by, contemporary post-Zionists challenging (to varying degrees) the legitimacy of a Jewish state. It also scrutinizes the various identity struggles within Israeli society, including the debate over defining a Jew, the rise of divergent and conflicting identities within the rubric of "Israeliness," the influence of postmodernism on Israeli and Jewish identities, and the challenge to Israeli identity that the "New Historians" posed beginning in the late 1980s. It further examines the onset of post-national, post-Zionist ideologies in the 1990s, encompassing the ever-growing trend to question the moral foundation, democratic nature and historical necessity of a Jewish state, and the increasing celebration of Diaspora as a conscious alternative to the Zionist notion of a national homeland. Finally, it analyzes the changes of Jewish identity within the United States as a result of a dramatic upsurge of American anti-Semitism in the first half of the twentieth century and the destruction of European Jewry in the Holocaust, the impact of power and religious fundamentalism on Israeli identity; and the ongoing debate over the elevation of Jewish national life in Israel as a higher plane of Jewish identity. It concludes that Jewish identity both in Israel and the Diaspora is today highly fluid and subject to profound change.