She was born Grace Purdie in Indianapolis. Moon received her education from the University of Wisconsin, National Academy of Design, New York and the Art Institute of Chicago. She spent several years in Europe and explored Aztec ruins in Mexico with her father. Her "bringing out" party was at the American Legation in Buenos Aires. In 1911 she married Carl Moon, a painter and photographer of the American Indian. Carl worked at El Tovar Studio in the Grand Canyon from 1911 until they moved to Pasadena in 1914. The couple had two children Francis-Maxwell and Mary. They collaborated on 22 children's books on the Pueblos and Navajos with Carl illustrating some of them.
White Indian - 1937, "The story is well-paced and not too far-fetched."
Solita -1938, "Grace Moon has established a reputation for this type of story, and though there is no particular distinction to this one, it is good routine story-adventure against a Mexican background."
Daughter of Thunder - 1942, "All Moon books give accurate pictures of Navajo life, showing various customs such as the Rain Dance."