Dorothy began inconspicuously enough in Omaha, Nebraska on June 14, 1916. Her parents encouraged her early interest in acting and she made her debut as a teenager in "A Kiss for Cinderella" at the Omaha Community Playhouse which starred visiting alumni member Henry Fonda. She received her education at Omaha Junior College, Ladywood Convent in Indianapolis, and Pine Manor Junior College in Wellesley, Massachusetts before setting her sites on an acting career. Following summer stock she appeared in such 1938 stage productions as "Bachelor Born" and "Stopover" before understudying the role of Emily Gibb in Thornton Wilder's "Our Town" on Broadway, which at the time showcased young Martha Scott. Dorothy eventually replaced Scott in the role.
Other experiences came her way on stage with "My Dear Children" starring John Barrymore, "Swingin' the Dream", "Medicine Show", "The Time of Your Life" and "Kind Lady" before she was handed the titular role of "Claudia" in 1941. This gentle comedy became a certifiable Broadway hit and Dorothy simply incandescent as the child-like bride forced to wake up to reality after her sudden marriage. David O. Selznick subsequently signed her to a film contract. Fortunately, 20th Century-Fox, untrue to form, took a chance on the film unknown and allowed her to recreate her stage triumph opposite Robert Young. Claudia (1943) was so beautifully done and warmly received that McGuire and Young went on to recreate their roles three years later with Claudia and David (1946).
In later years Dorothy found rich, rewarding work on TV and received an Emmy nomination for the well-received mini-series "Rich Man, Poor Man" (1976). She also played Marmee in a TV revisitation of Little Women (1978) (TV), and ended her career in good company with (what else?) a sentimental tearjerker in the mini-movie The Last Best Year (1990) (TV) co-starring Bernadette Peters and Mary Tyler Moore.
Dorothy's longtime husband was photographer John Swope who died in 1979. Her children by him are Mark Swope, an artist and photographer, and former actress Topo Swope. Dorothy's health declined severely after she fell and broke her leg in 2001. She died of heart failure not long after in a Santa Monica hospital on September 13th at the age of 85.