American educator, psychologist, and one of the leaders of the progressive education movement.

Irwin attended Smith College (B.A., 1903) and became involved in the social-settlement movement, working in New York City. From 1905 to 1909 she worked at odd jobs and as a free-lance journalist, writing about slum conditions in the city. In 1911 she began working as a “visiting teacher,” or social worker, for the Public Education Association of New York City (founded 1894). While working for the association as a psychologist, Irwin in 1916 initiated a program of testing and grading according to mental ability. Her next and perhaps best-known innovation was an experiment dubbed the “Little Red School House” (1921). This program continued for 10 years. It revised the standard curriculum, incorporating elements of play and group activities and varying the teaching methods, placing less emphasis on strictly academic learning. Financial considerations and other objections finally forced Irwin's program out of the public school in 1932, but many of her ideas on progressive education were later adapted to public school education. Irwin also wrote a number of articles on progressive education, drawing attention to a child's social and emotional development as well as academic growth.