Stephen Pierce Hayden Duggan (December 20, 1870, New York City - August 18, 1950, Stamford, Connecticut) was a United States scholar and educator known as the “apostle of internationalism.”
He was educated at the College of the City of New York (CCNY) where, after completing his undergraduate and some graduate work in 1896, he began teaching while pursuing graduate studies at Columbia University, where he received a Ph.D. in 1902. He was a professor of diplomatic history and later the history of education at CCNY, and became head of the education department in 1906.
Duggan founded The Institute of International Education in 1919, together with Nobel Laureates Elihu Root and Nicholas Murray Butler, and was the first director (until 1946). He was director of Council on Foreign Relations (1921–1950).