Paul Foster graduated from the U.S. Naval Academy at Annapolis, Class of 1911. Recalled to active duty during World War II, Foster was promoted to Captain and assigned to the Logistics Plans Division of the Office of the Chief of Naval Operations. He was later the Assistant Naval Inspector General and a member of the Navy Manpower Survey Board. He retired with the rank of Vice Admiral in December 1946. Foster joined the Atomic Energy Commission in June 1954 as a special assistant, becoming its General Manager four years later. In 1959, President Dwight D. Eisenhower appointed him to the International Atomic Energy Agency, in Vienna, Austria, with the rank of Ambassador, and he served in that position until 1961.