[4] At 17, she returned to New York City to study acting under the guidance of Sanford Meisner at the Neighborhood Playhouse, and made her Broadway debut in the short-lived 1961 comedy Everybody Loves Opal, for which she won a Theatre World Award.

[5] Vaccaro's Broadway credits include The Affair (1962), Cactus Flower (1965), the musical How Now, Dow Jones (1967), The Goodbye People (1968), the female version of The Odd Couple (1985), and Jake's Women (1992).

[8] Vaccaro appeared with Dustin Hoffman and Jon Voight in the 1969 film Midnight Cowboy, for which she was nominated for a Golden Globe Award for Best Supporting Actress.

[9][10] Additional screen credits include Airport '77; Capricorn One; The Pride of Jesse Hallam, Supergirl; The Mirror Has Two Faces; Heart of Midnight; Zorro, The Gay Blade; and Death Weekend, also known as House by the Lake.

After ill health forced Valerie Harper to bow out of the production of Nice Work If You Can Get It at the Ogunquit Playhouse (Maine), Vaccaro took over the role of Millicent Winter for the remaining performances of the limited run from August 4–15, 2015.