Smith was born in Paris, France, and raised in Washington, D.C., USA. She is the daughter (and namesake) of Joseph Yeardley "Joe" Smith (May 10, 1931–January 17, 2006), The Washington Post's first official obituary editor (1977–1988), who continued working full-time for The Post until 1996.
In addition to performing as the voice of Lisa Simpson and other occasional characters on The Simpsons, Smith also appeared on the sitcoms Herman's Head and Dharma and Greg and guest-starred on Showtime's Dead Like Me, the Disney Channel's Phil of the Future as well as a guest appearance on Teen Angel, and the "Mathnet" segment of the Children's Television Workshop show Square One.
Yeardley admitted on The Jane Pauley Show that she had struggled with bulimia for 25 years. Coincidentally, her character Lisa Simpson suffered through an eating disorder in the episode "Sleeping with the Enemy". She is currently performing in a one-woman show called More where she exposes her eating disorder. Yeardley has been binge-purge free for three years as of February 18, 2006.
A twist of trivia regarding her work on The Simpsons was that she auditioned for the role of Bart Simpson, while Nancy Cartwright auditioned for the part of Lisa. However the producers felt that Smith would be better suited for Lisa's voice, while Cartwright was given the role of Bart.
- The Simpsons Movie (2007) (voice)
- The Simpsons: Hit & Run (2003) (video game) (voice)
- Back by Midnight (2002)
- As Good as It Gets (1997)
- Jingle All the Way (1996) (uncredited)
- We're Back! A Dinosaur's Story (film) (1993)
- Toys (1992)
- City Slickers (1991)
- Maximum Overdrive (1986)
- The Legend of Billie Jean (1985)
- Heaven Help Us (1985)
- Yeardley Smith at the Internet Movie Database (IMDB)
- The Daily Targum’s interview with Yeardley Smith in 1997 (from The Simpsons Archive)
- Simpsons Illustrated’s interview with Yeardley Smith in 1992 (from The Simpsons Archive)
- Yeardley Smith's interview in Newsweek, discussing her one-woman show More and her struggles with bulimia
- Yeardley Smith at Voice Chasers