The Shepherd Wedding is the first significant event in the Gossip Girl television adaptation.
Summary
Prior to Pilot, Serena, Nate, Chuck, and Blair all attended the Shepherd Wedding and it's reception, held at Michael Jordan's Steakhouse in the Grand Central Terminal. During the reception, Blair sent Serena and Nate to the bar to sober up but the two end up having sex; and Nate to lose his virginity to Serena, unbeknownst to Blair. After the deed, Serena quickly left and headed to a hotel where she met up with Georgina and Pete Fairman. Soon after, Pete died from a cocaine overdose in front of Serena. Feeling guilty, she leaves town for The Knightley School in Cornwall, Connecticut.
In the season five finale The Return of the Ring, Serena and Dan attend The Shepherd's Divorce Party held at the same location, and the two have sex; causing Dan to cheat on Blair.