Joining her twin sister for a night of fashionable fun, Mary-Kate Olsen hit up “The Model as Muse: Embodying Fashion” Costume Institute Gala in New York City on Monday (May 4).

Held at The Metropolitan Museum of Art, the “Full House” hottie showed up clad in Christian Lacroix, sashaying her way through the press line and inside for the night’s festivities.

As previously reported by Gossip Girls, the night’s festivities are being hosted by Justin Timberlake, Kate Moss, Marc Jacobs and Anna Wintour.

All for a charitable cause, MK Olsen joins fellow guests including Victoria Beckham, Madonna, Kate Hudson and Jessica Alba, among many others.