This chapter provides a background on the preconciliar work that led to the declaration Nostra Aetate, drawing on the main existing historiographical literature, from the memories of John M. Oesterreicher to the theological reflection of Eugene Fisher, to the historical work of Giovanni Miccoli and Mauro Velati in the History of Vatican II edited by Giuseppe Alberigo. The long and difficult struggle that led to Nostra Aetate has great significance for the history of the Second Vatican Council: that document would become a document on all religions, and as such it would be received in the postconciliar period; in its origins, however, we find more problematic issues concerning the relationship between the Catholic Church and Judaism. Judaism has become the paradigm not only of interreligious dialogue, but also the paradigm of every difference, the sacrament of all otherness, the locus theologicus where the Christians can show that every “other” alludes in its very alterity to the One who is totally other and yet is totally close to every woman and to every man.