Pastel on gouache paper. Historical Society of Pennsylvania Collection, Philadelphia History Museum at the Atwater Kent, Philadelphia, PA.
Peggy Shippen (1760 - 1804), daughter of Edward Shippen — a moderate Loyalist who later became Chief Justice of Pennsylvania from 1799 to 1805 — married Benedict Arnold, 20 years her senior, when she was 18.
Pictured with her is either their only daughter, Sophia Matilda Arnold (b. 1785), or, since young boys also wore dresses at that time, possiblly it is their son, Edwin Shippen Arnold (b. 1780).