From 1845–1850, Purvis served as president of the Pennsylvania Anti-Slavery Society, a biracial organization. As a supporter of the Underground Railroad, Purvis served as chairman of the General Vigilance Committee from 1852–1857, which gave direct aid to fugitive slaves. According to his records, Purvis estimated that from 1831–61, he helped one slave per day achieve freedom, aiding a total of more than 9,000 slaves to escape to the North. He used his own house, then located outside the city, in Byberry Township, as a station on the Underground Railroad. Purvis built Byberry Hall on the edge of the Quaker Owned, Byberry Friends Meeting campus. Byberry Hall, which still stands today, hosted anti-slavery speakers and was just across the street from Purvis' home.