Below are the directors of the OI.
- Catherine E. Kelly, 2021—present
- Karin Wulf, 2013–2021
- Ronald Hoffman, 1992–2013
- Jean B. Lee, 1989–1991
- Thad W. Tate, 1972–1989
- Stephen G. Kurtz, 1969–1972
- Lester J. Cappon, 1955–1969
- Lyman H. Butterfield, 1951–1954
- Carl Bridenbaugh, 1945–1950