American educator, author, and editor who, as a leading “Essentialist,” opposed many of the practices of progressive education.

Bagley received his undergraduate degree in 1895 from the Agricultural College of the State of Michigan (East Lansing; now Michigan State University). After taking graduate courses at the University of Chicago and the University of Wisconsin (Madison), he earned a doctorate in psychology and education from Cornell University, Ithaca, N.Y., in 1900. Bagley's extensive practical experience in education included teaching in a one-teacher school in rural Michigan, administering public schools in several cities, and serving as professor of education at the University of Illinois at Urbana-Champaign (1908–17) and Columbia University (1917–40).

Bagley's lifelong professional commitment was to the improvement of public education, largely through improved teacher training. He became a leading spokesman of the “Essentialists”—a group of professional educators who advocated European-style emphasis on a rigorous curriculum of traditional subjects, in opposition to the approach of many progressive-education circles. He was an outspoken proponent of equality in educational opportunity and vigorously opposed restricting such opportunity on the basis of intelligence-test scores. He was an early experimenter in the use of radio for instruction.

Bagley's early publications included textbooks with Charles A. Beard, The History of the American People (1918) and Our Old World Background (1922), and a work with Beard and Roy F. Nichols, America, Yesterday and Today (1938). Among his own titles are Craftsmanship in Teaching (1911), School Discipline (1914), Determinism in Education (1925), Education, Crime, and Social Progress (1931), Education and Emergent Man (1934), and A Century of the Universal School (1937). Bagley also founded and edited many professional journals, including School and Society (1939–46).