This chapter reviews the question on what Jews are for. It talks about the anxiety over the long-term viability of Judaism that threatened to overwhelm the question across much of the Jewish world in the late twentieth century. It describes the European Jewish life in the aftermath of the Holocaust that was shadowed by a sense of dutiful traditionalism and anxiety over the continued presence of antisemitism. The chapter also analyzes the temptation and increasing ease of assimilation that was perceived as a threat to Jewish continuity in Europe, in the United States, and elsewhere in the New World. It points out how it was clear to some Jewish leaders, while faced with the prospect of a “vanishing diaspora,” that the postwar focus on communal survival lacked the inspirational power to renew Jewish life.