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Mariska Hargitay welcomed friends Hilary Swank and Debra Messing to celebrate with her at the fifth annual Joyful Revolution Gala New York City, in honor of the organization she founded, the Joyful Heart Foundation. The non-profit focuses on supporting survivors of sexual assault, domestic violence, and child abuse, a cause that Hargitay became well-acquainted with after working on Law & Order: SVU. Click through to see more stars who stepped out for last night’s hottest parties.

That’s what friends are for! Hilary Swank, Bridget Moynahan and Hugh Jackman were among the stars who turned out to support Law & Order: SVU star Mariska Hargitay at the 2011 Joyful Heart Foundation gala in New York City. Further downtown, Mary-Kate and Ashley Olsen stopped at designer Diane von Furstenberg‘s studio for the annual CFDA members’ meeting before heading over to the Tribeca Grand Hotel to join Rachel McAdams at the Cinema Society’s screening of Midnight in Paris. And speaking of Paris (Hilton, that is) the original celebrity socialite hyped her upcoming reality show at the Hollywood Roosevelt Hotel in L.A. Click through the gallery to see these stars plus Kate Moss, Naomi Campbell and more celebrities inside last night’s hottest parties!  

Kate Middleton and Prince William shared their first kiss as a married couple today! The new Duke and Duchess of Cambridge took their positions on the Buckingham Palace balcony for their smooch, along with Middleton’s family and Queen Elizabeth II. Prince William first planted a quick peck on Middleton, and then went back for a longer second liplock after he heard the crowd chanting “Give her another kiss!” He did, which led the fans below to erupt in cheers. How sweet! Click through the gallery to see more celebrity wedding kisses!

MORE:
• Kate Middleton’s Wedding Dress
• The Royal Wedding Guest List
• InStyle‘s Royal Wedding Live Blog