She began acting professionally at age three, with a national commercial for Shake 'N' Bake. Then she got a role in The Prophet's Game. In 2000 Taylor got the role of Cindy Lou Who in How the Grinch Stole Christmas. Two years later she got parts in two more motion pictures: Hansel & Gretel, in which she played Gretel, and Spy Kids 2: Island of Lost Dreams, in which she played Alexandra, the President's daughter. Taylor's career came to a halt for over three years until she got the lead role in the never-aired WB series Misconceptions. In 2002, Momsen recorded "Rudolph the Red-Nosed Reindeer" & "One Small Voice" featuring Myra & Camille Winbush for School's Out! Christmas
Momsen is in the 2006 films Doubting Thomas and Saving Shiloh. Her next film was Underdog, produced by Walt Disney Pictures. As of September 19th, 2007, she plays the character of Jenny Humphrey in the television series Gossip Girl. [Wiki]
