William Trufant Foster (January 18, 1879 – October 8, 1950), was an American educator and economist, whose theories were especially influential in the 1920s. He was the first president of Reed College.
Foster was born in Boston, Massachusetts on January 18, 1879. He graduated from Harvard University with an A.B. in 1901 and an A.M., 1904. Foster was an instructor of English at Bates College in Maine, from 1901–03 and served as a coach of Bates' internationally known debate program. Foster was also professor of English and Argumentation at Bowdoin College in Maine in 1905. He authored "Argumentation and Debating", published in 1908. Foster eventually received a Ph.D. in 1911 from Teachers College, Columbia University. His conception of "the ideal college" set out in the concluding chapter of his dissertation, led to his appointment as the first president of Reed College, 1911–1919. He rejected intercollegiate sports and fostered close intellectual collaboration between faculty and students. He was director (1920–1950) of the Pollak Foundation of Economic Research, in Newton, Massachusetts, where he emphasized the need to protect consumer interests.
He collaborated with his Harvard classmate Waddill Catchings in a series of economics books that were highly influential in the United States in the 1920s. His influential books, written with Catchings, were Money (1923), Profits (1925), Business Without a Buyer (1927), The Road to Plenty (1928), and Progress and Plenty (1930).