Chlumsky entered show business at an early age modeling with her mother in an advertising campaign. She is best known for playing Vada Sultenfuss in the 1991 movie My Girl and the 1994 sequel My Girl 2. She was in Gold Diggers: The Secret of Bear Mountain with Christina Ricci, and screen tested for the part of 'Lex' in Jurassic Park which eventually went to Ariana Richards. Columbia Pictures expressed serious interest in My Girl 3 (also known as Still My Girl) and a script has been in development since 2003, according to series co-star Dan Aykroyd. Aykroyd revealed in media outlets that Columbia was attempting to sign Chlumsky for the role. The project is still in development stages, with no current updates in four years. Chlumsky appeared on the March 8, 2007 episode of 30 Rock called "The Fighting Irish". She played the character "Liz Lemler". She also appeared as "Mary Calvin" in an episode of theNBC drama series Law & Order (Season 17, Episode 12) first airing January 12, 2007. She was also in three episodes of the ABC dramedy Cupid. Chlumsky starred in the Off-Broadway production of Unconditional by Brett C. Leonard at The Public Theater. It was produced by Philip Seymour Hoffman's theater group, LAByrinth Theater Company, which opened on February 2008. She appeared in the BBC Films political satire In The Loop, co-starring with The Sopranos' James Gandolfini. She plays Liza, a State Department assistant in the movie directed byArmando Iannucci.
1st Anniversary Celebration of our 70/70 Horovitz Project featuring a reading of Israel Horovitz's Unexpected Tenderness directed by acclaimed director Terry Kinney will take place on Wednesday, March 31st, 2010 at the Bleecker Street Theater.