Student, American School Dance, 1947-1954; student, Mount San Antonio Junior College, Walnut, California, 1956-1958; drama scholar, University of Southern California, 1958-1960.
She had a long association with Robert Altman, having written two of his most acclaimed films, Nashville (1975) and Thieves Like Us (1974). She has directed features, television movies, and television series. Tewkesbury was born in Redlands, California, the daughter of Frances M. (née Stevenson), a registered nurse, and Walter S. Tewkesbury, an office machine repairman.
She has lived in Tesuque, New Mexico since 2003. One of her early television acting roles was in a guest appearance on the short-lived NBC drama, It's a Man's World.
Member Literacy Volunteers American. Member Writers Guild American, Dirs. Guild American, American Civil Liberties Union, National Abortion Rights Action League, California Abortion Rights Action League. F C.
Married Robert F. Maguire, III, November 30, 1960 (divorced). Children: Robin Tewkesbury, Peter Harlan.