She was a professor and chair of the physical education department at Mills College from 1918 to 1947, and on the faculty at the University of California, Los Angeles (UCLA) from 1947 to 1962.

[1] She attended schools in Colorado Springs, Oakland,[2] and Tacoma, and graduated from Mills College in 1918, as a student of Elizabeth Rheem Stoner.

[5][6] Cassidy began teaching physical education courses at her alma mater, Mills College, immediately after graduating.

[5][9] Following in her mentor Elizabeth Rheem Stoner's footsteps, she promoted modern dance at Mills; she recruited Hanya Holm, Tina Flade, and Marian van Tuyl to teach at Mills in the 1930s, and she directed summer arts programs for dancers, writers, musicians, and visual artists.

[15][16][17][18] Cassidy received the Luther Halsey Gulick Award from the American Association for Health, Physical Education, and Recreation in 1956.