In the course of the nineteenth and early twentieth centuries, European Jewry experienced several major transformations. Traditionally a group apart in European society – living according to their own law in autonomous, self-governing communities, observing the rules and regulations of traditional Judaism, leading their lives according to the rhythms of the Jewish calendar, and speaking their own language, Yiddish – European Jews came to adopt, at least in part, the culture and social mores of the societies in which they lived. The process of acculturation involved significant change in what it meant to be a Jew.

In this period, Jews received political emancipation – equal economic, civil, and political rights with all other citizens. In return, they were required to adopt the culture and political loyalties of other citizens. Such demands for change were often ambiguous, and Jews transformed Judaism and Jewish identity in a variety of ways that depended on local conditions. Western and Central European Jews, who had received emancipation by 1870–1871, declared that they belonged to the dominant society and culture of their countries and that they differed from their fellow citizens only in matters of religion, a religion that they increasingly neglected to observe. At the same time, they continued to behave as if they belonged to a Jewish ethnic group.

In Eastern Europe, the home of the overwhelming majority of European Jews, emancipation came only with the Russian Revolution or the creation of new states at the end of World War I. Here most Jews continued to identify primarily as members of a Jewish nationality, even as many abandoned traditional Jewish religious practice and adopted Russian or Polish language and culture.