Joseph White Musser was the intellectual architect of Mormon Fundamentalism, who sought to preserve 19th-century traditions, such as plural marriage, as the Church of Jesus Christ of Latter-day Saints moved toward modernization. Following his 1921 excommunication, Musser became a prolific pamphleteer, meticulously compiling early teachings on the Adam-God doctrine and the 1886 Revelation to argue that priesthood authority remained with those who kept the “fundamentals.” His writings provided the theological glue for a displaced people, demonstrating that religious identity is often most sharply defined in conflict with the mainstream. In this interview, historian Cristina Rosetti explores Musser’s enduring influence on the fundamentalist movement.