 At Harvard, Zagorin was a student of Wilbur Kitchener Jordan, Charles McIlwain and others.He taught history at Amherst College (1947-1949), at Vassar College (1951-1953), and reached the rank of full Professor at McGill University, Montreal, while teaching there (1955-1965).The move to Canada resulted in part because of difficulties he encountered finding a tenure-track position in the U.S.A. because of his political beliefs, as McCarthyism threatened academic freedom.