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Gossip Girl co-stars Leighton Meester and Taylor Momsen each made appearances at New York’s Fashion Week, with Taylor taking in the Anna Sui show and Leighton hitting up the Proenza Schouler show.

Rachel Bilson is rumored to be engaged to boyfriend Hayden Christensen. Even though we took a close look at her sitting in the front row of the Bryan Reyes show, it was hard to tell if she was sporting a ring or not.

Tiny “boho-chic” fashionista Mary Kate Olsen was out with Nicole Richie, who with her thin, blond hair, wiry frame and big eyes could almost be mistaken for MK’s twin, Ashley Olsen.

Click on the “continue reading” link for a full list of which celebrity attended which show.

Gallery Info: Joshua Jackson, Diane Kruger, Selma Blair, Zoe Saldana, Mark Ramone, Natasha Bedingfield, Rachel Bilson, Ivanka Trump, Nicole Richie, Bee Schaffer, Leighton Meester, Mary Kate Olsen, Taylor Momsen, Rob Thomas, Jessica Szohr, Peaches Geldof, Angie Everhart, Kat De Luna, Kanye West, LL Cool J, Amanda Bynes, Mary J Blige, Sophia Bush, Mena Suvari, Michelle Trachtenberg, Elisabeth Hasselbeck, Julia Stiles, Jamie Lynn Sigler, Tori Spelling, Khloe Kardashian and Adrienne Bailon at Fall 2009 Fashion Week in New York.

Tommy Hilfiger: Joshua Jackson, Diane Kruger, Selma Blair, Zoe Saldana, Mark Ramone, Natasha Bedingfield Bryan Reyes: Rachel Bilson, Ivanka Trump Proenza Schouler: Nicole Richie, Bee Schaffer, Leighton Meester, Mary Kate OlsenAnna Sui: Taylor Momsen, Rob Thomas, Jessica Szohr, Peaches GeldofRichie Rich: Angie Everhart, Kat De LunaTory Burch: Kanye West, LL Cool J, Amanda BynesMalandrina: Mary J Blige, Sophia Bush, Mena Suvari, Michelle TrachtenbergMilly By Michelle Smith: Elisabeth Hasselbeck, Julia Stiles, Mary J BligeRebecca Taylor: Mena Suvari, Jamie Lynn Sigler, Tori Spelling, Khloe Kardashian, Adrienne Bailon