The organizational reaction to “unevangelical” elements in the urban population set the historical stage, just after the turn of the century, for the inauguration of an era of cooperation among Protestants (cf. Davis, 1973: 192) which was unprecedented in its attempts to integrate church work in areas as varied as religious education, foreign missions, domestic evangelization, and social action. “The first decade of the century,” commented Protestant researcher H. Paul Douglass (1934: 43), “is marked as an epoch of cooperation and federation.”

Chief among the signs of increasing cooperation was the founding, in 1908, of the Federal Council of the Churches of Christ in America. The Federal Council, the forerunner of the present-day National Council of Churches, joined thirty-three Protestant denominations in common spiritual and social causes (Hutchison, 1941; Sanford, 1916). Still other initiatives toward cooperation were undertaken even earlier. The standardization of Protestant Sunday School curricula was begun in 1900 with the guidance of the Editorial Association. The Laymen's Missionary Movement, organized in 1906, represented interdenominational collaboration in the administration of missions. And in 1908, the same year that the Federal Council was founded, domestic evangelism was coordinated for the first time on a large scale by the Home Missions Council and the Council of Women for Home Missions (Douglass, 1934: 43).

Widespread cooperation on social issues, much of it conducted under the auspices of the Federal Council, served as a prelude to a more sweeping movement for Protestant church union which gained momentum in the second and third decades of this century.