Appropriately enough, it was the continuing commitment of both Orthodox and Hicksite Friends to the peace testimony that paved the way for their gradual reconciliation and reunification. In 1901 they jointly organized a conference for world peace to which all American Quakers were invited.
Other developments in the early 1900s contributed to the reconciliation. In 1913, a group of Philadelphia young adult Friends from each branch began to meet regularly to study the separation and issued a report the next year stating that it was not a matter of doctrine but of authority that had caused the separation. The group continued to meet and to develop social occasions for young Friends of both branches to get together; this even resulted in a few cross-branch marriages. Women from both yearly meetings also worked together on issues of suffrage and peace; Alice Paul, a member of Moorestown Friends Meeting, was a leader in the campaign to pass and ratify the 19th Amendment.
In the early 20th century, revisions to both the Orthodox and Hicksite books of discipline included significant changes: disownment for marriage to a non-Friend ended; and, for the most part, there was no longer an emphasis on plain style of dress or speech. In 1916 a prominent Orthodox Friend in Philadelphia conveyed a letter of friendship from his own yearly meeting to the Hicksite Yearly Meeting. In 1917, members of both branches united with members of Five Years Meeting (now called Friends United Meeting) to organize the American Friends Service Committee to provide service opportunities for conscientious objectors in the First World War. AFSC sponsored a number of Civilian Public Service camps during World War II which enabled COs, including Friends from all yearly meetings, to pursue alternatives to military service. Quaker scholars on the faculties of Haverford and Swarthmore colleges and other universities achieved prominence beyond the Quaker domain and influenced the spread of modernism and activism. Establishment of the Friends Neighborhood Guild in 1879 (though named the Friends Mission No. 1 until 1899), Pendle Hill in 1930, Friends Council on Education in 1932, and the Friends Committee on National Legislation in 1943 also helped to form a bridge between Orthodox and Hicksite Friends. These organizations, particularly the AFSC, served to unify Friends and to develop a large cadre of Quaker leaders, including Douglas and Dorothy Steere, Howard and Anna Brinton, Rufus Jones and Henry Cadbury, who influenced Philadelphia Yearly Meeting Friends for decades to come.
In the 1930s and 1940s a number of committees of the two Philadelphia Yearly Meetings merged, such as a unified Peace Committee and a Religious Life Committee. The latter met for spiritual nourishment and also to prepare for visiting Friends meetings in both yearly meetings. At the same time, the disciplines of the two yearly meetings were revised in the direction of commonalities rather than differences and allowed for the formation of monthly meetings with membership in both Orthodox and Hicksite Yearly Meetings. An even more decisive step towards reconciliation was taken in 1946, when the two Philadelphia Yearly Meetings agreed to establish the Philadelphia General Meeting which would be held in the autumn and be attended by both Orthodox and Hicksite Friends, though separate sessions would continue to be held in the spring. Finally, in 1950, a committee was formed with representatives from both yearly meetings to prepare a common book of discipline. This committee submitted its work, entitled Faith and Practice, to both yearly meetings and to the General Meeting in 1954, and in 1955 the book was published. That year, a schism that had lasted for 128 years was amicably brought to an end, and a single, unified Philadelphia Yearly Meeting convened—with standing room only—at Arch Street Meeting House.