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Hilary Swank (in Marc Jacobs) showed her support for Fergie (in Calvin Klein) last night, who was honored with the Piaget Award of Inspiration at the amfAR Inspiration Gala, held at the New York Public Library. The honor, which recognizes her contributions to the fight against AIDS, was just one part of the mega-evening, which also included a performance by the Philadelphia Eagles cheerleaders, a live auction, and a men’s fashion show featuring 79 different looks inspired by the Olympics (think star-spangled Speedos). See more stars at last night’s hottest events in the gallery.

— Leah Abrahams, with reporting by Grace Lee

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!