She was an instructor at Wellesley College before joining the faculty of Stanford University, where she became the first full-time American professor of sociology.

[4] Mary Roberts taught at public and private schools from 1880 until 1886,[2][1] then was an instructor with the Department of History at Wellesley College until 1890.

In 1891, he was professor of machine design at the University of Wisconsin,[6] while she, along with former student Clelia Duel Mosher, continued research on the sexual practices of college women.

[12] It was a few months later in 1906 that she married a former student of hers, Dane Coolidge, a naturalist who would author a series of Western novels.

[15] For many years following her breakdown that significantly reduced her eminence in the field, Roberts was unable to gain employment in an academic position.

This changed in 1918 when she was hired as professor at Mills College, where she established the department of sociology and served as its first chair.