In 1847, three years after settling in Philadelphia,Still began working as a clerk for the Pennsylvania Anti-Slavery Society. When Philadelphia abolitionists organized a Vigilance Committee to directly aid escaped slaves who had reached the city, Still became its chairman. This led him and his wife Letitia to move to a relatively new rowhouse on the east side of Ronaldson Street between South and Bainbridge Streets, which still stands today at 625 S. Delhi Street. The Stills occupied this house, which was an Underground Railroad Way Station, from 1850 through 1855. Through his status as chairman of the Vigilance Committee, Still was one of the leaders of Philadelphia's African American community.