Mary Harkness, born in July of 1874, was married to Edward S. Harkness, the son of Commonwealth Fund founder Anna Harkness, in 1904. Upon entering the Harkness family, she became heavily involved in philanthropy, and under her vision, the Commonwealth Fund expanded its charitable giving to organizations that benefited cultural growth and social well-being.

In addition to her Commonwealth Fund philanthropic giving, Mary also donated personally to a wide variety of civic and cultural organizations, such as the New York Public Library, the New York Academy of Medicine, the Metropolitan Museum of Art, and Columbia University.

Upon her death in 1952, Mary willed her home, Harkness House, to the Commonwealth Fund which then became the Commonwealth Fund's headquarters.