This dissertation explores the unique, significant, and sometimes contentious relationship that existed between British Jewish author and activist Israel Zangwill and the Jewish community of the United States of America from 1892-1926 and beyond. Employing a broad definition of prophets and prophecy based on the works of prominent theologians, anthropologists, sociologists, and others, this dissertation argues that Zangwill's vision of America as a new, diasporic cultural and religious center was so significant that we may reasonably characterize him as a prophet of American Judaism. This dissertation carefully studies Zangwill's prophecy and the American Jewish reaction to Zangwillian thought to better understand both the nature of Zangwill's thinking and the American Jewish community's reception of that thought. In so doing it provides important insight into Zangwill's prophetic vision for America, as well as the American Jewish community's ideological divisions, limited tolerance for criticism, and anxieties over American toleration of Jews and Judaism in the Progressive era, the 1920s, and beyond. It places the narrative of Zangwill and America within the context of American Jewish intellectual history, as well as a broader, late-nineteenth-early- twentieth-century, trans-diasporic discourse on the prospective significance of America in Jewish life and culture. Of equal importance, this study carefully explores the phenomenon of modern fame as an important component in Zangwill's popularity and legitimacy in American Jewish discourse. It grants particular focus to the role that Israel Zangwill's American public played in determining the nature of Zangwill's fame, noting the ways in which Americans helped establish the late British Jewish author's reputation as an expert on Jews and Jewish affairs despite the fact that Zangwill preferred to be known as an artist unbound by the strictures of religion, nation, or tribe. In its conclusion, this dissertation considers the ways in which American Jews have written about and discussed Zangwill since his death. It notes the proclivity of twentieth-century, American Jewish intellectuals to reduce Zangwill's biography to a synecdochic device illustrating the supposed painful divisions of the modern Jewish personality, and it argues that this study, in conjunction with the recent works of literary scholars Edna Nahshon and Meri-Jane Rochelson, signals a new direction in the study of Israel Zangwill--an approach which recognizes his significant contributions to Anglo Jewish letters and discourse in his own day and in our contemporary historical moment, as well.