Once Brown finished her schooling at Antioch, she decided her calling was to be a minister. After countless rejections, she was accepted to the Theological School of St. Lawrence University, although the school's president, Ebenezer Fisher, made it clear he did not believe women should be ministers. She arrived on campus in 1861and graduated in 1863, becoming the first woman to graduate from an established theological school. Once again, Brown faced opposition from many sides. This included fellow students and the wives of the faculty. Brown took it all as a challenge. After her first year, Brown had gained acceptance and finished her schooling.