In June 2008 rumors surfaced about a possible spin-off based around the character Jenny Humphrey, based on the book series The It Girl, but Head Writer Josh Schwartz denied the claims, saying that there was nothing in development.
According to Variety in December 2008, "The CW may utilize an episode of Gossip Girl later this year to test the spinoff waters. The TV spinoff would nonetheless likely center on one of the show's nine regular characters -- although there's always a chance a new character could be planted in the backdoor pilot." 
However, Warner Bros. released a statement later in December 2008 saying, "Contrary to the rumors and false reports breaking in the tabloids, there is no approved concept and/or confirmation of a Gossip Girl spinoff at this time."
Schwartz and Savage are proceeding with a spinoff that will serve as a prequel to the sophomore drama and chronicle the wild teen years of Lily van der Woodsen in L.A. in the 1980s. The network has ordered a backdoor pilot for the project, which will air on May 11, 2009 and is tenatively to be called Lily. The 1980s world will be introduced in flashbacks tied to the episode's story line of Lily and her daughter Serena wrestling with a problem, Schwartz said. The spinoff is based on an original idea by Schwartz and Savage, who will exec produce it with Bob Levy and Leslie Morgenstein. Mark Piznarski is on tap to direct the spinoff.
The spinoff will outline the events that occurred between Lily and Rufus in their teen years. This will show the beginning of their relationship, including how they met, and their mysterious first child. Brittany Snow and Krysten Ritter have been respectively cast in the roles a young Lily and her wild child sister, Carol. The series is tentatively titled, Lily, and if the backdoor pilot is successful, should hit screens in the second half of 2009.
Brittany Snow as Lily Rhodes
Krysten Ritter as Carol Rhodes, Lily's "black sheep" older sister.
Shiloh Fernandez as Owen Campos, a possible love interest for Lily.
Andrew McCarthy as Rick Rhodes, Lily's father, a music company executive
Ryan Hansen as Shep, friend of Owen who will be crushing on Lily's older sister Carol.
Cynthia Watros as CeCe, Lily's mother.
Matt Barr as Keith van der Woodsen