Sienna Miller and Anna Wintour Get the Party Started in NYC

Thu., Aug. 20, 2009 6:11 PM PDT by Sydne Summer

Fashion's elite rubbed shoulders at the Museum of Modern Art last night celebrating the premiere of The September Issue, which highlights what it's like to work at Vogue. Anna Wintour, the star of the movie, went for her signature Prada prints. The contrasting trim of the dress is very much on trend—not that we'd expect anything less of the Vogue editrix. Sienna Miller, the magazine's actual September cover girl, looked like a Cinderella party princess in a Thakoon mini. The rest of the guest list included Renée Zellweger and her fave designer, Carolina Herrera, top models and fashion legends like Marc Jacobs, Oscar de la Renta and Vera Wang.

We can't wait to see the movie, which opens Aug. 28 in New York and Sept. 11 in Los Angeles and select cities. In the meantime, you can check out mystyle's Soiree Style gallery below to get your instant fashion fix!