The Ruin of Souls presents a new history of Italian Catholic life in the United States, from the founding of the first Italian Catholic church in the United States in 1853 to the end of the immigration flow as a result of the Emergency Quota Act of 1921. In this book, the product of wide research in American and Roman archives that spans the last twelve years, Di Gioacchino invites the reader to look at the religious history of the Italian Catholic immigrants in the United States not through the lens of their devotional culture, but through the perspective of their eccleasiastical life. More specifically, the book aims to document the efforts, problems, and failures of the Roman Catholic Church of the time to preserve the allegiance of the Italian immigrants in the United States to the Church’s magisterium and authority.  Strengthened by largely unknown archival documentation and an original historiographic methodology, the work reveals a new political dimension in the religious history of Italian immigrants in the United States and their relationship with the Catholic religious canon. By integrating the analysis of the ecclesial practices of the Italian communities into a far-reaching epistemological reflection, the work also contributes to the continuing discussion of how we study and examine the religious practices of Catholic communities in the modern era.