The day began around 2 p.m. when Lohan, her mother Dina, sister Ali and brother Dakota arrived at the Polaroid Beach House, a $30 million home the company has rented for the summer to throw events and host celebrities.
The actress, wearing a white bikini top and denim short-shorts, at one point took a beach stroll with her sister.
For most of the remainder of the day, Lohan and her family remained on the second-floor balcony overlooking the massive party that also drew JC Chasez, Maria Menounos, Amy Smart, Dave Navarro, Kevin Connolly, Kim Kardashian, Jennifer Finnigan and Jonathan Silverman, Jason Statham, Jeremy Piven and Matt Leinart.
A little before 5 p.m., Hilton came over from her own beach pad two houses over and greeted the guests. Wearing a blue floral-print dress, Hilton smiled and giggled – looking relaxed after her post-jail Maui vacation – before returning to her Spanish-style house without meeting Lohan.
That left the rest of the day for Lohan and family to listen to music (including a remix of Eminem’s “Shake That” and Kelly Clarkson’s “Since You’ve Been Gone”) and enjoy a half-hour fireworks show.
• Reporting by JENNIFER GARCIA