From 1991 to 1994, alongside "The Simpsons", Smith was one of the lead cast members in the sitcom "Herman's Head" as Louise. Her other television roles include recurring appearances as Marlene on "Dharma & Greg", and Penny in two episodes of "Dead Like Me". Smith has also appeared in "Phil of the Future" and "Teen Angel". Her one-scene role as pregnant checkout girl Nancy in 1991's "City Slickers" earned her "more attention than all previous roles combined", and taught her "that it's far better to have small parts in big movies that everyone sees." In 1997, she appeared as Lulu the palm reader in the independent film "Just Write". Her other roles include parts in Barry Levinson's "Toys" and James L. Brooks' "As Good as It Gets". Brooks, who is also executive producer of "The Simpsons", had cast Smith in his 1994 film "I'll Do Anything" (in one of the film's musical numbers), but her part was cut. Aside from "The Simpsons", Smith has recorded few voice-over parts, only commercials and the film "We're Back! A Dinosaur's Story". She "had a voice-over agent for about two years, and I used to go out [on auditions all the time, but it never really came to anything. Everybody said, 'Oh Yeardley, you'll clean up,' and that was definitely not the case."