From the perspective of historical sociology, Richard N. Juliani traces the role of religion in the lives and communities of Italian immigrants in Philadelphia from the 1850s to the early 1930s. By the end of the nineteenth century, Philadelphia had one of the largest Italian populations in the country. The Archdiocese of Philadelphia eventually established twenty-three parishes for the exclusive use of Italians. Juliani describes the role these parishes played in developing and anchoring an ethnic community and in shaping its members' new identity as Italian Americans during the years of mass migration from Italy to America.

Priest, Parish, and People blends the history of Monsignor Antonio Isoleri—pastor from 1870 to 1926 of St. Mary Magdalen dePazzi, the first Italian parish founded in the country—with that of the Italian immigrant community in Philadelphia. Relying on parish and archdiocesan records, secular and church newspapers, archives of religious orders, and Father Isoleri's personal papers, Juliani chronicles the history of St. Mary Magdalen dePazzi as it grew from immigrant refuge to a large, stable, ethnic community that anchored "Little Italy" in South Philadelphia. In charting that growth, Juliani also examines conflicts between laity and clergy and between clergy and church hierarchy, as well as the remarkable fifty-six-year career of Isoleri as a spiritual and secular leader. Priest, Parish, and People provides both the details of parish history in Philadelphia and the larger context of Italian-American Catholic history.