The privileged prep school teens learn that Serena van der Woodsen is back.

In the wake of a party, Serena receives an ice-cold reception from her best friend.

Blair uncovers information about Serena that may not remain a secret much longer.

Blair is thrilled when her mother chooses her to be the new face of her clothing line.

Dan makes elaborate plans to impress Serena on their first official date.

Dan is torn between two girls when his childhood friend Vanessa returns home.

Serena and Dan finally acknowledge that they are crazy about each other.

Blair puts on a happy face for her 17th birthday party.

Dan naively invites Serena and her family to celebrate Thanksgiving with his family.

Serena has no intention of attending the Ball, until it's announced that she must attend.

Blair's father comes home for the holidays with his boyfriend.

The gang breaks into the school swimming pool for an impromptu night of fun.

Gossip Girl reports that Serena van der Woodsen has been spotted buying a pregnancy test.

Blair returns to school after losing her Queen Bee status.

Michelle Trachtenberg guest stars as Serena's old friend.

One of the Upper East Side teens reveals that he's gay.

Serena falls back into old habits; Dan assumes the worst.

Blair and Georgina face off.