Ruth Nulton Moore was born in Easton, Pennsylvania, on June 19, 1923. Her parents were Jacob Wesley Nulton, a dentist, and Stella Houck Nulton. In 1946, she married Carl L. Moore, a professor of accounting and a writer, with whom she had two children: Carl Nulton and Stephen Eric.

Moore received an AB from Bucknell University in 1944 and an MAfrom Columbia University in 1945. In 1946, she went on to do further graduate study at the University of Pittsburgh.

Moore worked as a public school teacher of English and social studies in Easton, Pennsylvania, from 1946 to 1950 and as a high school English and social studies teacher in Detroit, Michigan, in 1952. In 1965, Moore found her true calling when she became a freelance writer and began to write children's literature. She published twenty-one children's novels.

Moore was named to the C.S. Lewis Honor Book List in 1983 for her book Danger in the Pines (1983).

Moore lived on a small farm in Bethlehem until her death on September 23, 2001, of Parkinson's disease.