The Roman Catholic Modernist Crisis erupted as the nineteenth century came to a close and the twentieth century began. Pope St. Pius X famously condemned "modernism" as "the synthesis of all heresies" in his 1907 papal encyclical Pascendi Dominici Gregis. Many may wonder whether or not modernism remains a relevant field of study. Roman Catholic Modernism and the Catholic Magisterium's response to Modernism, was a significant phase in twentieth-century Catholic theology and history, and it formed an essential part of the context necessary for understanding what led to the Second Vatican Council. This volume explores the continued relevance of Modernism, with a special focus on the contributions of Alfred Loisy, one of the pivotal figures within the history of the Modernist Crisis.