Grace Gallatin Seton-Thompson was born on January 28, 1879, in Sacramento, California, the youngest of three children of Albert and Clemenzie (Rhodes) Gallatin. Her parents were divorced in 1881, and Seton-Thompson subsequently moved with her mother to New York City, where she graduated from the Packer Collegiate Institute in 1892.
During a trip to Europe in 1894, she met Ernest Thompson Seton, a naturalist and writer. They married in 1896 and had one child, a daughter Ann, nicknamed Anya, who became a well-known writer. Seton-Thompson frequently accompanied her husband on camping trips, and in 1900 published her first book, A Woman Tenderfoot, describing her trip on horseback through the Rockies. She was instrumental in organizing a woman's motor unit in France during World War I, bringing food and other aid to soldiers. By the late 1920s, Seton had separated from her husband; they were divorced in 1935.
An active committeewoman and ardent suffragist, Seton-Thompson served as vice-president and later president of the Connecticut Woman Suffrage Association (1910-1920). She was president of the National League of American Pen Women (1926-1928 and 1930-1932), doubling the number of branches of that organization. As chair of letters of the National Council of Women (1933-1938), she established the Biblioteca Femina, a collection of 2,000 volumes by women from all over the world. The collection was later donated to the Northwestern University Library. She also belonged to the Women's National Republican Club, Pen and Brush, the Society of Woman Geographers, and other organizations.
Seton-Thompson traveled widely during the 1920s and 1930s, visiting Japan, China, Egypt, India, South America, and Indochina, frequenting areas where "all normalcy and security is gone." She wrote five books about her adventures, including A Woman Tenderfoot in Egypt (1923) and Poison Arrows (1938). Captivated by mysticism and eastern religions, she published The Singing Traveller (1947), a collection of poems expressing these beliefs. Seton-Thompson died in Palm Beach, Florida, in 1959. For further biographical information, see Notable American Women: The Modern Period (1980).