Raised by her maternal grandparents in Staunton, Virginia after her mother remarried, in 1842 Mary became a member of the first class of sixty girls at the Augusta Female Seminary.
During the American Civil War, the Augusta Female Seminary faced closure when its principal and his two daughters (both teachers) relocated to Texas.
The remaining trustees persuaded Baldwin (then operating a local school a year after her grandmother's death) to assume its leadership as principal in August 1863, with her long-time friend Agnes McClung as matron.
[1] After the war, aided by William Holmes McGuffey, professor of moral philosophy at the University of Virginia, and brother of teacher Eliza Howard, Baldwin improved the school's curriculum.
It came to include rhetoric, composition, higher mathematics, chemistry and physics, as well as topics traditionally taught to well-bred women such as music, visual arts, and elocution.