Her father was Robert Pearsall Smith, her mother Hannah Whitall Smith. She studied at the Harvard Annex in 1884-1885. Here Mary met the Irish barrister Benjamin "Frank" Conn Costelloe, whom she married in 1885. This marriage was the occasion for the whole family, including her brother Logan Pearsall Smith and sister Alys Pearsall Smith to move to England in 1888. Mary separated from Costelloe, with whom she had two children, after a few years together. She took up in Italy with Bernard Berenson, whom she eventually married in 1900. Her US lecture tours were instrumental in developing an interest in Italian Renaissance art among wealthy American collectors during the first decade of the twentieth century.
Subsequently, Berenson brought together a social circle at Villa I Tatti', the Berenson home, and developed its gardens. Through her daughters, Ray Strachey and Karin Stephen, she was related by marriage to the Bloomsbury Group of English artists and literary figures, as her son-in-law Adrian Stephen was Virginia Woolf's brother.
- "Dictionary of Art Historians - Mary Berenson". arthistorians.info. Retrieved 2016-03-28.
- Tiffany L. Johnston (2012). "Mary Whitall Smith at the Harvard Annex". Berenson and Harvard. The President and Fellows of Harvard College. Retrieved June 4, 2014.
- The Strachey Papers at the Archives in London and the M25 Area
- Adams., Pauline Maier; Pauline Maier Is Professor Of History At The Massachusetts Institute Of Technology Her Most Recent Book Is the Old Revolutionaries: Political Lives In The Age Of Samuel (1982-12-12). "A WORLD OF WOMEN". The New York Times. ISSN 0362-4331. Retrieved 2016-03-28.
- Johnston, Tiffany (2015). "Mary Berenson and the Cultivation of American Collectors," in A Market for Merchant Princes: Collecting Italian Renaissance Paintings in America. University Park, PA: Penn State University Press. p. 72. ISBN 978-0-271-06471-0.
- The garden of Villa I Tatti: some historical notes in The Harvard university Center for Italian Renaissance Studies Archived 2007-09-27 at the Wayback Machine
- Palmer, Alan (1987). Who's Who in Bloomsbury. New York: St. Martin's Press. pp. 17–18.
- Barbara Strachey and Jayne Samuels (1983), Mary Berenson: a Self Portrait from her Letters & Diaries