[3][4] During the Panic of 1837, DuBois persuaded her father-in-law to open an empty warehouse to accommodate men left homeless by the economic downturn.

In 1854 she and a doctor's wife, Anna R. Emmet, founded the Nursery and Child's Hospital, which focused on the needs of poor women and their small children.

[1] DuBois and Emmet ran the hospital with personal funds and energetic fundraising among her friends and in the wider community, including charity balls, until she successfully lobbied the New York state legislature for support.

She made miniature cameos, sometimes taught art classes, and was elected to the National Academy of Design.

[9] In 1832, Mary Ann Delafield was married to Cornelius DuBois (1810-1882), a lawyer and tobacco merchant.