U.S. educator, probably the most widely known public school educator and philosopher in the United States during the late 19th century.

Harris attended Yale College and after 1858 worked as a teacher and later as superintendent of schools in St. Louis, Mo. (1868–80). He served as U.S. commissioner of education from 1889 to 1906. As a practical school man, Harris was an effective administrator and reformer. He introduced into the curriculum such studies as art, music, science, and manual arts, and he favoured the professional study of education for teachers in training. He worked to extend the public high school and incorporated the kindergarten into the regular school system of St. Louis. In addition to serving as president of the National Education Association in 1875, Harris also presided over the National Association of School Superintendents (1873–80).

As a philosopher and psychologist, Harris was more synthetic than original, embracing German Idealism, American Transcendentalism, Christianity, phrenology, and mental discipline. He lectured for several summers at the Concord School of Philosophy, but Hegelian Idealism was retreating, and Harris was not creative enough to stem the rising tide of Naturalism. A prolific writer of several hundred philosophical and educational articles, Harris was also editor of The Journal of Speculative Philosophy (1867–93), Appleton's International Education Series, and Webster's New International Dictionary.