Vote on this week's styles including Blake Lively, Reese Witherspoon and
more stars! You decide – are they fashionistas or flops? By Andrea
DeSimone and Melissa Liebling-Goldberg
After celebrating her 21st birthday on the Gossip Girl set, the
actress gets all dressed up in a Christian Cota ombre dress to promote the
show's much-anticipated season premiere on The Late Show With David
Letterman.