Abby Morton was born in Plymouth, Massachusetts, the daughter of a wealthy shipbuilder and a descendant of one of the original Pilgrim families. Her father was interested in social reform and later took the family to live in an experimental utopian community organized by the Transcendentalist sect at Brook Farm, where Abby worked for a while as a teacher. In 1845, she married Manuel Diaz of Havana, with whom she had two sons. The marriage failed, and Mrs. Diaz turned to several occupations to support herself and her children. She became a nurse and a singing and dancing instructor. Her literary career began in 1861 with her story "Pink and Blue," published in the Atlantic Monthly. This was followed by many stories to instruct children, which appeared in the leading childrens' periodicals of the day. In 1870, she published one of her most successful and enduring books, The William Henry Letters, whose sequels, William Henry and His Friends (1872) and Lucy Maria (1874), were also very popular. Her books were noted for their good humor and affectionate tone. When her own children were grown, Abby Diaz became active as a social reformer. She helped organize the Boston Women’s Educational and Industrial Union in 1877 and served as its director and then president for many years. She joined the Association for the Advancement of Women along with Julia Ward Howe and lectured widely on women's suffrage. She also wrote The Schoolmaster’s Trunk (1874), and A Domestic Problem (1875).