Margaret Haley was born in Joliet, Illinois, on 15th November, 1861. Haley became a teacher in Chicago in 1876. An early member of the Chicago Teachers' Federation she became a full-time official in 1901.
Haley was also president of the National Federation of Teachers and used this organization to help develop the more important National Education Association. Haley led a long campaign for state pensions for teachers and this was successfully introduced in Illinois in 1907.
Haley became an organizer with the American Federation of Teachers when it was established in 1916. She also wrote and published the Margaret Haley Bulletin (1915-31).
Margaret Haley died in Chicago on 5th January, 1939.