In the April Conference of 1941 five men were called as Assistants to the Quorum of the Twelve Apostles. J. Reuben Clark, Jr., of the First Presidency explained at the conference that they had been called because of the rapid growth of the Church and the ever-expanding demands upon the Quorum of the Twelve. A total of thirty-eight men served the Church as Assistants to the Twelve before the office was merged with the Seventy in 1976.
    As General Authorities, Assistants to the Twelve had the authority to minister throughout the Church and to fulfill assignments as directed by the Quorum of the Twelve. They presided over, and spoke at stake conferences; helped organize stakes; toured missions; and directed missionary work in many parts of the world. Some were called as Apostles although not members of the Twelve while others served holding the priesthood office of High Priest.
    A number of men who first served as Assistants to the Twelve were later called to be members of the Quorum of the Twelve Apostles: George Q. Morris, Boyd K. Packer, Marvin J. Ashton, L. Tom Perry, David B. Haight, James E. Faust, Neal A. Maxwell, and Joseph B. Wirthlin. Several others who had served as assistants to the Twelve also served in the Quorum of the Twelve and later as Counselors in the First Presidency, including Hugh B. Brown, N. Eldon Tanner, Marion G. Romney, and Gordon B. Hinckley. And one, of course, President Gordon B. Hinckley, suceeded to the office of Pesident of the Church, becoming the Presiding High Priest in all the world.
    An important 1835 revelation on priesthood describes the Seventy as the quorum standing next in authority to the Twelve, and under their direction, the Seventy share responsibility for the Church throughout the world (D&C 107:25-26, 33-34). According to President Spencer W. Kimball in 1976, the calling of the Assistants was "similar to that envisioned by the revelations for the First Quorum of Seventy," but "the scope and demands of the work at that time [1941]" did not yet justify the reconstitution of that quorum. After accelerating growth in many parts of the world led to the organization of the First Quorum of Seventy in 1975, the nearly two dozen Assistants then serving became members of that quorum in 1976.

Marion G. Romney (1941-1951)
Thomas E. McKay (1941-1958)
Clifford E. Young (1941-1958)
Alma Sonne (1941-1976)
Nicholas G. Smith (1941-1945)
George Q. Morris (1951-1954)
Stayner Richards (1951-1953)
ElRay L. Christiansen (1951-1975)
John Longden (1951-1969)
Hugh B. Brown (1953-1958)
Sterling W. Sill (1954-1976)
Gordon B. Hinckley (1958-1961)
Henry D. Taylor (1958-1976)
William J. Critchlow, Jr. (1958-1968)
Alvin R. Dyer (1958-1967; 1970-1976)
N. Eldon Tanner (1960-1962)
Franklin D. Richards (1960-1976)
Theodore M. Burton (1960-1976)
H. Thorpe B. Isaacson (1961-1965; 1970)
Boyd K. Packer (1961-1970)
Bernard P. Brockbank (1962-1976)
James A. Cullimore (1966-1976)
Marion D. Hanks (1968-1976)
Marvin J. Ashton (1969-1971)
Joseph Anderson (1970-1976)
David B. Haight (1970-1976)
William H. Bennett (1970-1976)
John H. Vandenberg (1972-1976)
Robert L. Simpson (1972-1976)
O. Leslie Stone (1972-1976)
James E. Faust (1972-1976)
L. Tom Perry (1972-1974)
J. Thomas Fyans (1974-1976)
Neal A. Maxwell (1974-1976)
William Grant Bangerter (1975-1976)
Robert D. Hales (1975-1976)
Adney Y. Komatsu (1975-1976)
Joseph B. Wirthlin (1975-1976)