The Fundamentalist Church of Jesus Christ of Latter-Day Saints (FLDS Church) is one of the largest Mormon fundamentalist denominations and one of the largest organizations in the United States whose members practice polygyny. The FLDS Church emerged in the early twentieth century when its founding members left The Church of Jesus Christ of Latter-day Saints (LDS Church). The split occurred largely because of the LDS Church's suspension of the practice of polygamy and its decision to excommunicate its members who would continue the practice.