The B-day girl takes a second to pose on the red carpet before heading inside to party.
Brit's manager, Larry Rudolph, is on hand to wish the pop star a happy birthday along with Jive Records' head honcho, Barry Weiss.
Lipstick Jungle hottie Robert Buckley and Lance Bass enjoy some popcorn at Brit's circus-themed fete.
Blond bombshells Brit-Brit and Heidi Klum hang inside the bash. Brit made a surprise appearance at Heidi's Halloween party last year.
Newly single Jaime Pressly, who recently separated from fiancé Eric Cubiche, enjoys the soiree solo.
Brit poses with her umpteenth cake for the week. She already blew out the candles at a nightclub in London, on Good Morning America and at a dinner at the Rainbow Room, so she ate a tiny piece of this particular one. Wonder what she wished for?
Want more pics? See Britney's amazing comeback transformation!