Mary Yost was born in Staunton, Virginia on September 25, 1881 and graduated from Vassar College in 1904.

After a year teaching English at Wellesley College, she went back to Vassar to study a master's degree.

She moved to Stanford University four years later to take up the position of associate professor of English and Dean of Women, which she held until her retirement in 1946.

[1] Yost was an honorary member in Cap and Gown, an honor society for women undergraduates founded by Edith R. Mirrielees.

On retirement she was awarded an honorary LL.D from Mills College "in recognition of her long service to women".