In histories of American Presbyterianism, the southern branch of the New School Church has received little attention despite its importance to church history as a whole. This new study provides a complete account of the southern church, tracing the events and controversies that led to schism, the founding of the United Synod, and eventual reunification with the Old School, South. The author begins by reviewing the causes of the original and Old School-New School schism of 1837-1838 and the circumstances that gradually deepened the separation between the northern and southern wings of the New School. The emergence of United Synod of the South and its activities in the antebellum period and during the Civil War are considered next. The author concludes with a discussion of the final union with the Southern Presbyterian Church in 1864 and assesses the reasons why the southern New School/United Synod failed to grow and reach the potential of other Presbyterian churches of that day.