A pixish singer-dancer-actress, with a sometimes squeaky voice which still has a lilt of an East Texas accent, Duncan made her stage debut before she was a teenager in a Dallas production of "The King and I" (1958). She made her Broadway debut in 1965 in a revival of "The Music Man", one of the first of several musicals in which she appeared at the City Center Theatre. Duncan briefly returned to Broadway replacing Twiggy as leading lady to Tommy Tune in "My One and Only".
In 1971. Duncan made a stab at leading roles in films. She played wife to research scientist Dean Jones in her debut, "The $1,000,000 Duck" (1971), and was the sweetness and light heroine involved with two radical guys in "The Star Spangled Girl" (also 1971), adapted from a Neil Simon play. Most of her subsequent credits, however, have been confined to providing the voices for animated characters, such as Vixey in "The Fox and the Hound" (1981), Peepers in "Rock-a-Doodle" (1992), and Queen Uberta in "The Swan Princess" (1994). Mostly, Duncan found her niche on stage and TV. She had her own shot at a series with "Funny Face" (CBS, 1971), which was revamped and renamed "The Sandy Duncan Show" the next year. In 1987, she joined what was then called "Valerie's Family" (NBC) after Valerie Harper left her sitcom in a contractual dispute. Her best work in longforms was probably as Miss Anne, the young woman of the plantation who teaches Kunte Kinte's daughter, Kizzy (Leslie Uggams) to read, but then denounces Kizzy when she refuses to be her servant in the groundbreaking ABC miniseries "Roots" (1977). She joined Judith Light and Jill Eikenberry as one-time members of a one-hit girl singing group who reunite for a TV show in "My Boyfriend's Back" (NBC, 1989). Additionally, Duncan has hosted the "Macy's Thanksgiving Parade" (NBC, 1988) and the "Miss Teen USA Pageant" (CBS, 1990) as well as making numerous appearances on variety and award shows. More recently, she was one of the celebrity participants in "Gail Sheehy's New Passages" (ABC, 1996).