Gratz was the seventh of twelve children born to Miriam Simon and Michael Gratz. Her mother was the daughter of Joseph Simon, a preeminent Jewish merchant of Lancaster, while her father immigrated to America in 1752 from Langendorf, in German-speaking Silesia. Michael, who was descended from a long line of respected rabbis, and Miriam were observant Jews and active members of Philadelphia’s first synagogue, Mikveh Israel.
In 1801, at the age of 20, she helped establish the Female Association for the Relief of Women and Children in Reduced Circumstances, which helped women whose families were suffering after the American Revolutionary War. In 1815, after seeing the need for an institution for orphans in Philadelphia, she was among those instrumental in founding the Philadelphia Orphan Asylum. Four years later, she was elected secretary of its Board. She continued to hold this office for forty years. Under Gratz' auspices, a "Hebrew Sunday School" was started in 1838. Gratz became both its superintendent and president, and assisted in developing its curriculum, resigning in 1864.
Gratz was also one of the founding members of the Female Hebrew Benevolent Society, around November 1819. In 1850, she advocated in The Occident, over the signature A Daughter of Israel, for the foundation of a Jewish foster home. Her advocacy was largely instrumental in the establishment of such a home in 1855. Other organizations that came about due to her efforts were the Fuel Society and the Sewing Society.
Gratz is said to have been the model of Rebecca, the daughter of the Jewish merchant Isaac of York, who is the heroine in the novel Ivanhoe by Sir Walter Scott. Scott's attention had been drawn to Gratz's character by Washington Irving, who was a close friend of the Gratz family. The claim has been disputed, but it has also been well sustained in an article entitled "The Original of Rebecca in Ivanhoe", which appeared in The Century Magazine, 1882, pp. 679–682.
Gratz never married. Among the marriage offers she received was one from a Gentile whom she loved, but ultimately chose not to marry, on the account of her faith. Her portrait was painted twice by the noted American artist Thomas Sully. One of those portraits, both owned by the Rosenbach Museum, is on display at the National Museum of American Jewish History.
Shortly after Rebecca Gratz died in 1869, her brother, Hyman, founded and financed Gratz College, a teachers’ college in Philadelphia, in her memory.
- David B. Green (27 August 2013). "Pioneering philanthropist and educator dies". This day in Jewish history. Haaretz Newspaper. Retrieved 4 September 2013.
- Burlingame, Dwight F. (ed.) (2004). Philanthropy in America: A Comprehensive Historical Encyclopedia, Vol. 1, pp. 215-16. ABC-CLIO, Inc. ISBN 1-57607-860-4.
- "Ivanhoe" Legend Rebecca Gratz, 1781 – 1869 - entry in the Jewish Women's Archive (retrieved 2010-9-25)
- Judith Mindiy Lewin: Legends of Rebecca: Ivanhoe, Dynamic Identification, and the Portraits of Rebecca Gratz. In Nashim: A Journal of Jewish Women's Studies & Gender Issues, Number 10, Fall 5766/2006, ISSN 0793-8934
- Portrait of Rebecca Gratz, Rosenbach Museum (retrieved 2011-1-7)