Reese is ready to party!

Reese Witherspoon has been out and about in the daylight hours -- running errands, cheering on son Deacon's soccer game -- since welcoming son Tennessee James Sept. 27.

But the evening of Friday Oct. 26 marked the Devil's Knot star's first official night out since becoming a mom for the third time. Clad in a blue shift dress and ankle booties, the 37-year-old was among the bevy of A-listers on hand for the opening of Rag and Bone's new flagship store in Los Angeles.

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Sans husband Jim Toth, Witherspoon had a gal pal to lean on: Cameron Diaz, wearing head-to-toe Rag and Bone, with her hair pooled back into a messy ponytail.

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Witherspoon and Diaz -- both pals to Rag and Bone designers David Neville and Marcus Wainwright, not to mention Gwyneth Paltrow and Chelsea Handler -- were all smiles as they sipped champagne and caught up at the bash.

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Other star at the bash include Emma Roberts and boyfriend Evan Peters (American Horror Story: Asylum), Mad Men's Kiernan Shipka, Mandy Moore, Vogue's Anna Wintour and daughter Bee Schaffer, Brittany Snow and Aziz Ansari.

This article originally appeared on Reese Witherspoon Beams Alongside Cameron Diaz on First Night Out Post-Baby