Around the turn of the twentieth century, revivalist Protestantism in America splintered into multiple pieces. Few persons of that era knew as many of the central figures of the splinter groups as Aaron Merritt Hills. Originally a Congregationalist who studied under Finney at Oberlin, Hills was a dyed-in-the-wool postmillennial revivalist until his death in 1935. While a Congregationalist, he befriended Reuben A. Torrey and made an enemy of Washington Gladden. In 1895 he joined the Holiness Movement after his experience of Spirit baptism. For the next forty years he founded colleges, held holiness revivals in both America and Britain, and wrote voluminously. While Hills himself is a lesser-known figure in the story of American Christianity, because of the many embroilments of his life, his story offers a unique window into the relationship between the Holiness Movement, Fundamentalism, Pentecostalism, American liberalism, and the Social Gospel Movement.