This is an exploration of the relationship between Jews and magnates in the Polish-Lithuanian commonwealth, in which Rosman shows the influence of the Jews on economic, social and political life in the Polish, Ukranian and Belorussian territories. Rosman focuses on two questions: What were the principal spheres of interaction between the Jews and the nobility? What was the significance of this interaction for both parties? By analyzing the Sieniawski-Czartoryski estates the author demonstrates the measure of co-operation that existed between magnates and Jews. Jews guaranteed the viability of important economic institutions and provided commercial services, while magnates furnished an environment for Jews to conduct their religious and commercial activities. Drawing on Polish, Hebrew and Yiddish sources and literature from archives and libraries in Poland, Israel and the United States, Rosman provides a detailed account of the socioeconomic development of early modern Europe's largest Jewish community.