With her pooch in tow, the Gossip Girl star celebrates her 21st b-day on the New York City set of her show. Plus: Ashlee Simpson, Lindsay Lohan, Paris Hilton and more

MEET THE MOMS

Lindsay Lohan shares dinner with mom Dina, girlfriend Samantha Ronson (not pictured) and her mom, Ann Dexter Jones, at Bar Pitti, in New York's West Village on Sunday night.