Rachel Bilson is a Bridesmaid Beauty

Rachel Bilson serves at the maid of honor at the wedding of her longtime best friend Jill Stonerock on Saturday at a ranch in Santa Barbara, Calif. (For this special occasion, Rachel, 27, designed her own the bridesmaids’ dresses with designer Brian Reyes.)

Jill married 32-year-old Josh Schwartz, the creator of The O.C., Gossip Girl and Chuck. Rachel was a series regular on The O.C. and has made cameo appearances on Chuck (Season premiere on Monday, Sept. 29).

10+ pictures inside of blushing bridesmaid Rachel Bilson…