The article examines the evolution of organized Jewish communities in the United States during the second half of the 19th century. After discussing why the historiography tends to focus on New York, the beginnings of the organized Jewish community in Chicago serves as a case study to highlight the challenges Jewish immigrants faced as they tried to build communities. Landsmanshaft, class, religion, voluntary membership, and the enormous size and diversity of urban Jewish populations after 1850 precluded the recreation of tight-knit European-style communities. By avoiding sources of conflict, notably religion, the traditional social tasks of the community emerged as the smallest common denominator bringing Jews of different backgrounds together on a single platform.