Nancy Cartwright writes first Simpsons episode

Actress Nancy Cartwright has been the voice of Bart Simpson for decades. Now she's moving into new territory.

A special episode of the Simpsons airs Sunday. It's the first one the veteran actress has written.

The episode is about Lisa's wish to join a prestigious band. Her lovingly dysfunctional family makes sacrifices -- as all families do -- so she can follow her dreams.

"To be honest with you, I never saw myself as a writer on the show," Cartwright said. "I had a lot of support from the writers. I was like, 'Oh my gosh. I have no idea how to do this.' They were a big help in contributing to it."

Although Cartwright is known for being the voice of Bart, she's also behind the microphone for other characters like school bully Nelson Muntz, Ralph Wiggum and the young innocent Todd Flanders.