Colby joined the CIA in November 1950. His first assignment was in the Western European Division, of the Office of Policy Coordination (OPC). In 1951, he became the OPC's representative in Stockholm.
He became Deputy Chief of Station, Saigon in 1959.
In 1960, he became Chief of Station, Saigon.
He was appointed Deputy Chief, Far East Division, DDP, in 1962, becoming chief of the division later the same year.
In 1968, he was assigned to the Agency for International Development as Deputy Director of Civil Operations and Rural Development (CORDS), Saigon. Later the same year, he was appointed Director, CORDS (with the rank of Ambassador), Vietnam.
In 1972, Colby became CIA's Executive Director-Comptroller.
- Office of Strategic Services
- Central Intelligence Agency
- Committee on the Present Danger (1976 version)
- Namebase COLBY WILLIAM EGAN
- Edward Jay Epstein, The War Within The CIA, Commentary, August 1978, archived at EdwardJayEpstein.com
- R. Harris Smith, OSS: The Secret History of America's First Intelligence Agency, University of California Press, 1972, p.202.
- Harold P. Ford, William Colby: Retrospect, Studies in Intelligence, Semiannual Edition, No. 1, 1997, Center for the Study of Intelligence, CIA.