MONDAY, JULY 20

"GOSSIP GIRL" � (9:00-10:00 p.m. ET)

"The Magnificent Archibalds" (TV-14) (HDTV)

THANKSGIVING ON THE UPPER EAST SIDE � Thanksgiving in the Waldorf household finds Blair (Leighton Meester) upset that her mom's (Margaret Colin) new boyfriend, Cyrus (guest star Wallace Shawn), has decided to ruin all her favorite traditions, but that's nothing compared to what's coming next. Lily (Kelly Rutherford) finds herself trying to broker a peace treaty between Rufus (Matthew Settle) and Jenny (Taylor Momsen) who is prepared to cut off all communication with her father if she doesn't get her way. Serena (Blake Lively) isn't quite ready to come clean with Aaron (guest star John Patrick Amedori) about her complicated past, but Dan (Penn Badgley) ends up accidentally revealing a few tidbits of his own. Blair and Chuck (Ed Westwick) come to their friend's aid when Nate (Chace Crawford) is once again forced to confront his father's (guest star Sam Robards) abandonment. Finally, Eric (Connor Paolo) discovers a secret that Bart (Robert John Burke) has been keeping from Lily. Jessica Szohr also stars. Jean DeSegonzac directed the episode written by Joshua Safran (#211).