Rachel Bilson, alongside The O.C. creator Josh Schwartz and executive producer Stephanie Savage, celebrated the 21st anniversary of the iconic series at a party in West Hollywood. The event featured a live performance by Phantom Planet, whose song 'California' served as the show’s theme song. Bilson also launched the 'The O.C. x 21Seeds' campaign, reprising her role as Summer Roberts, which included new promotional videos. For the occasion, she donned a striking pink Valentino dress paired with matching platform pumps, embodying the show's nostalgia and modern fashion trends. Schwartz expressed excitement about revisiting the character of Summer and hinted at hidden references from the show in the new campaign. The event highlighted both the cultural impact of The O.C. and the ongoing connection between its cast, creators, and fans.