In 1937 he earned a bachelor's degree in psychology from the University of California, Los Angeles, where he had also been an editor of the Daily Bruin. He then worked at the University Religious Conference, which promoted inter-religious cooperation. In that position he met Eleanor Roosevelt, who recruited him as chairman of the youth division of the Office of Civilian Defense in Washington, D.C.
He wrote two books, “A Timeless Affair: The Life of Anita McCormick Blaine” (University of Chicago Press, 1979), a biography of his grandmother-in-law; and “The Enthusiast: A Life of Thornton Wilder” (Ticknor & Fields, 1983).
Harrison received a George Polk Award in 1964 for his work in revitalizing The New Republic.