Inside Olivia Culpo's Pretty Little Thing Party

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The hot parties were in Los Angeles this week.

Olivia Culpo headed to Hollywood's Liaison Lounge on Thursday night, where she was on hand to celebrate her capsule collection with U.K.-based brand PrettyLittleThing. There, she kept it cool in a white shirt she styled with a black leather mini-skirt, open-toe booties, a rectangular clutch, and, of course, a bold red lip. Rita Ora took the stage at the party to perform "Your Song," so you know it was a good time.

At Hotel Bel-Air, Heidi Klum reminded us that yes, she is indeed a designer. The supermodel took over the space for a "bra brunch" in celebration of her latest Heidi Klum intimates campaign. She kept it casual in jeans, a white shirt, and a flower in her hair.

Stars kicked off the celebrations over the weekend at producer Jennifer Klein's home, where they flocked for her annual Day of Indulgence. Ciara, Lily Collins, Kerry Washington, and Rashida Jones came together for lots of pampering and catching up.

RELATED: Olivia Culpo's Chic Vacation-Ready Swimsuits

Back in New York, young things Dylan Sprouse and Tavi Gevinson headed out for the premiere of Patti Cake$. Though they arrived separately, they both matched in a black top with classic blue jeans. Sometimes, the basics are the best sartorial choice.

Scroll down for the best parties of the week.

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Heidi Klum

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at her Heidi Klum Intimates campaign celebration.

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Rashida Jones and Kerry Washington

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at the 19th annual Day of Indulgence.

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Lily Collins and Ciara

Amy Graves

at the 19th annual Day of Indulgence.

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Tavi Gevinson

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at the premiere of Patti Cake$.

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Dylan Sprouse

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at the premiere of Patti Cake$.

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Danielle Macdonald and Bridget Everett

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at the premiere of Patti Cake$.

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Star-Studded: The Best Parties This Week