Grace Thorpe Gemberling Keast was born in Philadelphia in 1903. She received her training at the Pennsylvania Academy of the Fine Arts under Hugh Breckenridge where she was twice awarded the coveted Cresson Traveling Scholarship. Keast was also the recipient of the Mary Smith Prize for best painting by a Philadelphia woman artist, and the Fellowship Prize for her still life, Gourds, from the Academy in 1940.
Keast lived in Bala Cynwyd, a suburb in the Main Line section of Philadelphia, where she maintained a studio and taught painting. She was a painter of landscape, still life and figurative subjects. Her style was distinct, leaning slightly towards modernist while remaining realistic, evoking a mysterious and eerie quality within her work.
Keast exhibited at the Salons of America, the National Association of Women Painters and Sculptors, the Society of Independent Artists and the Corcoran Gallery Biennials.