Newlyweds Blake Lively and Ryan Reynolds were back in wedding mode over the weekend -- but this time, the nuptials weren't their own.

The couple attended Blake's "Sisterhood of the Traveling Pants" costar Amber Tamblyn's wedding to "Arrested Development" star David Cross.

The two were snapped at the outdoor affair by Questlove of The Roots, who tweeted photos of all the stars at the ceremony.

Fellow costars America Ferrera and Alexis Bledel also attended, as well as Amy Poehler, Jason Ritter and "30 Rock" star Kristen Schaal.

Questlove's photos also give us a much better look at Amber's wedding dress (which was yellow!) and some cute moments with her new (and much older) husband.

Amber, 29, and Cross, 48, finally made it official after dating for about 4 years.

The couple also attended Blake and Ryan's wedding last month.