The Fourfold Gospel, most often associated with Albert B. Simpson, founder of The Christian and Missionary Alliance, which focuses on the doctrines of Christ as Savior, Sanctifier, Healer, and Coming King, has been identified as a key contributing factor to the birth and development of the modern Pentecostal movement. Through a close observation of the doctrinal themes of select and renowned Evangelical leaders in America (A. J. Gordon of Boston, D. L. Moody of Chicago, A. T. Pierson of Philadelphia/Detroit, and A. B. Simpson of New York), this work shows that the Fourfold Gospel and, therefore, the theological source for modern Pentecostalism, rather than being a marginal movement within late nineteenth-century Evangelicalism was, instead, its very heart.