Mabel Major, teacher, poet, and scholar of southwestern folklore and literature, was born on September 20, probably in 1893, in Ogden, Utah, the daughter of David E. and Mollie (Ashcraft) Major. She grew up in Missouri and earned a B.A. from the University of Missouri in 1914 before teaching high school English at Higginsville, Missouri. She returned to the university to earn B.S. and M.A. degrees in 1916 and 1917, and then moved to Texas in 1917 to teach English at Big Spring High School. In 1919 she joined the faculty of Texas Christian University, where she remained for forty-four years, until her retirement in 1963. Periodically, she pursued graduate study at the University of Chicago (1926), the University of California at Berkeley (1928), and Columbia University (1946). She was awarded an honorary doctor of literature degree by TCU in 1964.
At TCU, Major become one of the state's early scholars of southwestern literature and folklore as well as a specialist in the works of Shakespeare, Tennyson, and Browning. Her university course on southwestern literature was among the first, preceded only by J. Frank Dobie's With another TCU faculty member, Rebecca W. Smith, Major edited a high-school anthology of southwestern literature in 1929 and, with Smith and T. M. Pearce of the University of New Mexico, wrote the first general literary history of the southwest, Southwest Heritage: A Literary History with Bibliography (1938; revised 1948, 1972). Also with Smith, Major edited the stories and reminiscences of Texas frontiersmen W. S. (Bronco Bill) Bartlett and John C. Duval and Duval's account of the life of William A. A. (Big Foot) Wallace. Her "British Ballads of Texas" appeared in Tone the Bell Easy, a Texas Folklore Society publication edited by Dobie in 1932. An anthology of southwestern poetry, another collaboration with Pearce, appeared in 1950 as Signature of the Sun: Southwest Verse, 1900–1950.
While Major wrote a variety of shorter works, including monographs, poetry, book reviews, personal essays, and scholarly articles, Southwest Heritage remained her best-known publication. She was active in the Texas Folklore Society, which she served as vice president in 1933 and 1936 and as president in 1937. From 1947 to 1949 she was vice president of the Texas Institute of Letters. In 1953–54 she served as the president of the Texas Conference of College Teachers of English. She was promoted to professor in 1938, served as acting chairman of the English department from 1943 to 1946, coedited the university's literary journal, Descant, and spent the last sixteen years of her career at TCU as chairman of the creative writing committee, in which role she supervised the formation of a program in creative writing.
In 1964, the year after her retirement from TCU, Major received an award from Theta Sigma Chi for her contributions to southwestern literature and was also named Piper Professor by the Minnie Stevens Piper Foundation for her research on the life of poet and playwright Frank Desprez. After her retirement, Major taught southwestern literature at Baylor University and was a visiting professor at New Mexico State University and at San Fernando (California) State College. She was a member of the University Christian Church (Disciples of Christ), the Fort Worth Women's Club, and Delta Delta Delta. At her death on June 3, 1974, she left unfinished research on Desprez and Susan Elsten Wallace and bequeathed $10,000 to TCU as a scholarship fund for students of southwestern literature.