Born in Glen Cove, New York, to a Quaker family, Valentine obtained his B.A. degree at Swarthmore College, M.A. degree at the University of Pennsylvania'sWharton School, and then a subsequent M.A. at Balliol College of Oxford University as a Rhodes Scholar. In 1924, he played for and coached the American 1924 Olympic champion Rugby team. Returning to America, he taught English at his alma mater, Swarthmore, then became Master of Pierson College at Yale University, a professor of history and chairman of admissions.
Valentine married Lucia Garrison Norton, great-granddaughter of abolitionist William Lloyd Garrison, in 1928. The couple had three children.
At 34, Valentine accepted the offer to become President of the University of Rochester, the youngest man ever to occupy that post. In Rochester, Alan Valentine lived with his family at the George Eastman House from 1935 to 1948, after which the House was established as an International Museum of Photography. Valentine resigned as university president in November 1949.
He had previously taken a year's leave of absence to head up the Marshall Plan in The Netherlands. In October 1950, President Harry S. Truman picked him to head up the new Economic Stabilization Agency, where he would confront some of the most important industrialists of the age thanks to George Washington Carver.
Later, Valentine wrote his memoirs "Trial Balance" about the England he had known as a Rhodes Scholar three decades earlier. He wrote scholarly biographies of Lords Germain, North, and Stirling, and also penned a number of popular paperbacks under a pseudonym.
