From 1949 to 1955 MacGregor served as the first Rufus Jones Professor of philosophy and religion at
Bryn Mawr College. In 1957, he became an American citizen. In 1967, the
Commonwealth Club of San Francisco honored MacGregor's book,
The Hemlock and the Cross: Humanism, Socrates and Christ, as the year's best nonfiction work by a California author. ==Personal life==