[2] After an education in exclusive Californian private schools,[3] her theatrical debut was with her mother in Liliom, a play produced by the Sombrero Theater, in Phoenix, Arizona, in April 1955 and with the husband-and-wife team of Fernando Lamas and Arlene Dahl.

"[7] On 13 March 1957, Stevenson was cast in CBS's Playhouse 90 adaptation of Charley's Aunt, with Tom Tryon, Jackie Coogan, and Jeanette MacDonald.

Stevenson played Peggy McTavish in the film Darby's Rangers (1958), a Warner Bros. release in which she was paired with Peter Brown.

[13] Stevenson also had a primary role in the film version of the Studs Lonigan trilogy by James T. Farrell, brought to the screen in December 1960.

[14] Among the other motion pictures in which she appears are Island of Lost Women (1959), Jet Over the Atlantic (1959), The Big Night (1960), Seven Ways from Sundown (1960), The City of the Dead (or Horror Hotel, 1960), and The Sergeant Was a Lady (1961).

[citation needed] Stevenson appeared on television in episodes of Cheyenne (1957), Colt .45 (1958), 77 Sunset Strip (1958), The Adventures of Ozzie and Harriet (1958), Lawman (1958), The Millionaire (1959), The Third Man (1959), and Alfred Hitchcock Presents (1960) alongside Burt Reynolds and Harry Dean Stanton.

[12][15] Stevenson married MGM actor-dancer Russ Tamblyn on Valentine's Day, 1956, shortly after her half-brother, actor Jeffrey Byron, was born to her mother.

[17] A widely reproduced photograph shows Stevenson calmly walking down a Los Angeles street, seemingly unaware that Tamblyn is doing a spectacular backward aerial handspring a few inches away from her.