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Mariska Hargitay‘s hair looked extra soft and smooth at Baby Buggy’s Bedtime Bash in New York City recently, all thanks to her favorite hair product—Terax Crema conditioner! “Feel my hair, it’s so healthy,” she said to us at the charity event. It was! “It’s been blow dried every day for 13 years. But since I’ve been using Terax, when I blow it out it’s so silky. It’s my go-to.” Score your own bottle for $22 at beauty.com.

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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!