Olaf C. Christiansen (August 12, 1901 – April 12, 1984) was an American composer, professor, and conductor in the Lutheran choral tradition.

Upon graduation, Christiansen briefly studied opera in New York City with baritone Paul Parks.

[2] After obtaining a master of sacred music degree from Union Theological Seminary in 1940, he returned to his alma mater in 1941 to co-conduct the St. Olaf Choir with his father.

Upon his father's retirement in 1943, he became the full time conductor of the St. Olaf Choir, a position he held until 1968[3] During his career, Christiansen spread the Lutheran choral tradition across the nation.

In addition to domestic and international tours with the St. Olaf Choir, he co-founded the Christiansen Choral School with his father, which was attended by more than 7,000 American music directors.