Mary McCauley Maxwell was born in Moody, Texas, on October 8, 1884. She attended Baylor Female College (now the University of Mary-Hardin Baylor), graduating in 1904. She then attended Baylor University, where she was a member of the Calliopean Literary Society and graduated in 1908. She served as the head of the History Department at Baylor Female College until she married F. O. Maxwell in 1913. The couple later had three children.
Mary McCauley Maxwell developed an interest in Judge R. E. B. Baylor, one of the founders of both of her alma maters, and in the 1930s, and she began to collect his relics. She donated the items to Baylor University at the 90th Commencement in 1935. Because of her research and contact with the Baylor family, she persuaded them to donate several valuable family relics to Baylor University as well.
Maxwell was one of the primary people working to preserve Baylor's original campus in Independence, Texas. She also persuaded the Centennial Commission to give $14,000 to Baylor for a statue of Judge R. E. B. Baylor, eventually created by Pompeo Coppini. She was invited to join the State Historical Society in 1954. Mary McCauley Maxwell died in Waco on January 31, 1963.
More information about Mary McCauley Maxwell can be found in the Mary McCauley Maxwell papers at The Texas Collection.