The daughter of famed Washington Post obituaries editor, Joseph Yeardley Smith, Martha Maria Yeardley Smith was born July 3, 1964 in Paris, France. Immigrating to the U.S. two years later, she was raised in the nation’s capital, where her father worked. There, Smith grew up a shy, introverted child. Finding herself drawn to performing in her early teens, Smith landed an apprenticeship at the renowned Arena Stage in Washington, D.C. after high school, before heading off to New York to seek her fortune. In 1984, Smith made her professional debut on Broadway as Debbie Reynolds’s understudy in Tom Stoppard's "The Real Thing."

Parlaying her success into film roles, Smith made her screen debut the following year in Michael Dinner’s teen cult favorite “Heaven Help Us” (1985). Later that year, Smith made a memorable turn as Helen Slater’s loud-mouthed friend, Putter, in “The Legend of Billie Jean” (1985), a featherweight action-drama directed by Matthew Robbins. Driven by a blaring rock soundtrack, “Billie Jean” was expected to go over big with MTV audiences. Unfortunately, the film was a huge bomb. Undeterred, Smith moved to Los Angeles full-time in 1986, settling into theatre work with appearances in L.A. stage productions of "Boys and Girls/Men and Women" and British playwright Alan Ayckbourne’s “How the Other Half Loves." Around the same time, Smith also landed a recurring role on television, playing Luella Waters on the landmark cable comedy series, "Brothers" (Showtime, 1984-89).

In the late 1980’s, after having lost out on a number of roles due to her distinctive, high-pitched chirpy voice, Smith won the role of her career. This time, however, it was Smith’s voice that proved the deciding factor in booking the job. In late 1987, Smith found work as a voice artist on a series of crude, but exceptionally well-received, animated shorts by “Life Is Hell” cartoonist, Matt Groening. Called “The Simpsons,” these shorts were aired exclusively on the Emmy-winning sketch comedy series, “The Tracey Ullman Show” (Fox, 1987-1990). The shorts gained such a cult following that eventually their segments increased, sometimes three to four per episode. As “The Simpsons” took on a life of its own, so too did their visibility in the media. By the 1988-89 season, the cartoon family received co-star billing at the top of each show alongside Ullman herself. While the character designs were extremely primitive and voice characterizations were still in flux at this stage, the series gradually evolved. The artwork, in particular, improved dramatically. Plots generally stemmed from the mundane (such as son Bart going to get a haircut) to the more absurd (such as Homer hypnotizing the kids into behaving).

In 1989, following a highly rated primetime Christmas special, Fox launched the Simpsons into their own series. Titled simply “The Simpsons,” Smith returned to reprise her role as Lisa, the family’s sane-minded, overachieving daughter. Joining Smith were “Ullman Show” alums Dan Castellenata (as hapless paterfamilias, Homer), Julie Kavner (as devoted wife and mother, Marge), and Nancy Cartwright (as the bratty firstborn, Bart).

With the runaway success of “The Simpsons,” Smith quickly faced a wealth of options. On a career hot-streak, Smith landed a second gig as a regular on the inventive ensemble comedy “Herman’s Head” (Fox, 1991-94). After the cancellation of “Herman’s Head,” Smith maintained an impressively busy schedule. While continuing her work on the Fox hit, Smith logged over a dozen guest appearances on various other television shows throughout the 1990’s. At the same time, the actress got a chance to flex her comedic muscles on the big screen. In addition to appearing in small roles in such films as “City Slickers (1991) and “Toys” (1992), Smith had a scene-stealing turn in 1997’s “As Good As It Gets” starring Oscar winner Jack Nicholson.

As the new millennium dawned, Smith’s job prospects looked brighter than ever. In 2002, while simultaneously juggling her 14th season on “The Simpsons,” Smith returned to live-action series television with her recurring role as Thomas Gibson’s lovesick secretary, Marlene, on the marital comedy “Dharma & Greg” (ABC, 1997-2002). In 2004, Smith turned up again on the small screen as Penny the Reaper for a two-episode arc on the short-lived cable dramedy “Dead Like Me” (Showtime, 2003-04).

Throughout her career, however, Smith never strayed far from her day job. In her career-defining role as the sax-playing Lisa Simpson, Smith became a part of television-history when “The Simpsons” became the longest-running sitcom in American TV history. In the mid-2000’s, the popularity of “The Simpsons” was still sufficiently high enough that rumors of a Simpsons feature film went into overdrive. In 2006, 20th Century Fox confirmed that a feature-length movie was indeed in the works for a likely release of the summer of 2007.