Mary Sargant Florence was born in London. She studied art in Paris and at the Slade School in London. Her brother F.W. Sargant became a sculptor. In 1888, she married Henry Smyth Florence, an American musician, with whom she had two children, Philip Sargant Florence, who became an American economist; and Alix Strachey, the psychoanalyst and translator of Freud. As a painter, Mary Sargant Florence is known for her works Children at Chess (c.1903), Suffer Little Children to Come unto Me (1913) and Pentecost (c.1913). She painted fresco decorations at the Old School, Oakham, Rutland, and at Bournville School near Birmingham. She was a suffragist, feminist, supporter of the Women's Tax Resistance League, and a member of the committee for the Hague Peace Congress of 1915. She designed her house, Lordswood, in Buckinghamshire, where she hoped to found an artists' colony, and where she lived until 1940. She published a book on militarism and feminism with Charles Kay Ogden, and wrote Colour Co-Ordination (1940), a work on the history, theory and aesthetics of colour. She also edited two volumes of the Papers of the Society of Painters in Tempera.