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

In the wake of the scandalous Kiss on the Lips party, Serena receives an icy cold reception from Blair.

Blair uncovers scandalous information about Serena; Dan sets his sights on impressing the Dartmouth representative.

Blair is thrilled when her mother, Eleanor, chooses her to be the new face of her clothing line; Serena and Dan are reminded once again that they come from two very different worlds; Nate and Chuck indulge in a boys' weekend to blow off steam after Ivy Week.

Dan makes elaborate plans to impress Serena on their first official date; Jenny is invited to the infamous Blair Waldorf sleepover and finds herself in a high-stakes game of truth or dare; Lily discovers Eric missing from his treatment center, and seeks help from her ex-boyfriend, Rufus.

Dan is torn between two girls when his childhood friend Vanessa returns home and declares her feelings for him

Serena and Dan finally acknowledge they are crazy about each other; Jenny discovers a secret about her parents; Blair is once again devastated by Nate's actions.

Blair puts on a happy face for her 17th birthday party and attempts to hide the truth from her friends.

When Dan finds out that Serena and her family are celebrating Thanksgiving alone, he naively invites them to spend the holiday with his family.

As 'Gossip Girl' posts news of the annual Cotillion Ball to take place on the approaching weekend, Blair decides not to go with Nate, but she finds herself being featured in The New York Times and is enjoying her secret affair with Chuck. Serena decides not to go either, so her grandmother, CeCe, shows up to change her mind. Meanwhile, Jenny volunteers for the ball and Lily takes her under her wing. But the night of The Cotillion is the night of Alison's first art opening, and Rufus and Alison tell Jenny that she cannot attend the ball. Jenny decides to defy them both by secretly attending the dance anyway. Refreshed by Blair's newly buoyant attitude, Nate asks her to the Cotillion and she accepts, which makes Chuck jealous. CeCe tells Lily and Serena that she is sick with lung cancer and her last dying wish is to see Serena go to the ball, and she wants Serena to go with the wealthy Carter Baizen. The snobbish CeCe takes an instant dislike to Dan and she approaches Rufus with an offer pay him to convince Dan not to go with Serena. Dan learns of this and tells Serena that he does not think very highly of CeCe by telling Serena about how CeCe tried to bribe his father to persuade him not to attend. Surprisingly, the skeptic Serena refuses to believe Dan that her compassionate grandmother is a crafty snob, and she ends up going to the ball with Carter... both her and Dan having fallen right into CeCe's ploy. Also, Chuck manipulates Nate into thinking Carter is having an affair with Blair to provoke a fight with him.

Blair's father comes home for the holidays with an unexpected guest; Jenny and Vanessa help Serena plan the best Christmas surprise ever for Dan.

The gang breaks into the school swimming pool, but when one of them nearly drowns, the school threatens to expel the ones who broke-in.

Gossip Girl takes pleasure in reporting that Serena has been spotted buying a pregnancy test, and word spreads like wildfire.

Blair returns to school after losing Queen Bee status; Serena's not fond of living with her future stepbrother, Chuck.

Serena's world is turned upside down when her former partner in crime, Georgina Sparks, returns to Manhattan to stir up trouble.

Blair and Jenny escalate their "popularity war" by spreading scandalous rumors about each other through Gossip Girl.

Georgina reveals the true reason that Serena fled Manhattan for boarding school, and Serena quickly falls back into her old habits.

With Serena's reputation on the line, Blair takes matters into her own hands to deal with manipulative Georgina.

Gossip Girl heads to the Hamptons as summer comes to a close; Serena and Nate fake a relationship as a cover for Nate's affair with a married woman.

Blair is thrilled to be dating royalty, but a scheming Chuck has other plans for her; Serena and Dan agree to keep their recent hookups a secret.

Serena and Dan must deal with their problems while trapped in an elevator; Blair and Chuck question the lack of passion in their relationships.

When Dan starts getting cozy with Amanda, the new girl at school, Serena turns to Blair and her minions to step in to sabotage her chances. Vanessa also enlists Blair's help when she finds out a scandalous secret about Catherine.

Blair sabotages her mother's show at Fashion Week; Dan starts hanging out with Chuck, and learns that a walk on the dark side always has risks.

Serena decides to visit Yale and gets even with Blair. Dan learns that none of his recommendation letters made it to Yale.

Blair seeks revenge by enticing Chuck to seduce Vanessa; Serena rebels at a party of Lily's; Dan and Jenny find out a secret Nate has been hiding.

Jenny befriends a model, and is encouraged to explore her wild side; Serena is attracted to an artist, Aaron Rose.

Serena realizes Aaron has kept a secret from her; Jenny and Agnes plan a guerilla fashion show; Blair baby-sits the daughter of a Yale donor.

Dan tries to get close to Bart Bass to possibly write an exposé, but things get heated when Chuck finds out.

Blair's favorite Thanksgiving traditions are ruined by her mother's new boyfriend; Serena doesn't tell Aaron about her past -- but Dan does.

The teens prepare for the annual Snowflake Ball, a charity event for prep school seniors.

A sudden and tragic event impacts the lives of everyone on the Upper East Side, especially Chuck and the van der Woodsens.

Chuck's uncle, Jack Bass, arrives on the scene; Jenny returns to school and takes on the mean girls.

Bart's will is read and everyone learns the fate of the Bass empire; Dan discovers the secret between Rufus and Lily.

The seniors try to find out who is worthy of an early admission to Yale; Chuck pairs up with an unlikely ally in his war with Jack over Bass Industries.

Blair comes up with a plan to get revenge on her teacher; Chuck wakes up in a hotel and tries to piece together what happened the night before.

The seniors put on a production of "The Age of Innocence"; Chuck enlists help from an unlikely source -- his nemesis, Carter Baizen.

Devastated by the recent plot twist in her life, Blair turns her back on her predictable existence in favor of a wilder lifestyle.

Serena throws Jenny a party for her 16th birthday, but things get out of control when Poppy Lifton turns the small gathering into a huge social event.

Serena returns from her trip to Spain with Poppy and Gabriel; Blair makes a secret deal with Nate's grandfather; Dan gets a job.

Georgina returns; Chuck and Nate are at a crossroads in their friendship -- a result of their mutual interest in Blair.

Blair pressures Georgina to help her in a scheme; Nate and Chuck's rivalry over Blair comes to a head; Lily hatches a secret plan to help Rufus.

To prove her independence, Serena refuses to leave jail with her mother or her grandmother; Rufus is furious with Lily for having Serena arrested.

Gossip Girl livens things up at graduation by sending out a shocking email blast during the ceremony.

Blair and Chuck adjust to their new status as a couple; Serena returns from Europe with many secrets and a complicated relationship with Carter.

Blair begins NYU, determined to keep her Queen Bee status, but Georgina has other ideas; Serena recruits Carter to get even with Chuck.

It's Blair versus Chuck as they both set their sights on a particular item up for bid at Sotheby's; Georgina takes an interest in Dan.

It's Jenny's first day as Queen Bee; A famous actress, Olivia Burke, is assigned as Vanessa's roommate.

Lily and Rufus move up their wedding, but complications threaten to tear them apart; Chuck discovers a secret Carter has been keeping from Serena; Dan and Vanessa are pulled into one of Georgina's schemes.

Dan invites Olivia to meet Rufus and Lily, which leads to all sorts of problems for the new couple; Serena and Nate team up to help Carter Baizen.

Serena helps Chuck open his club, but Blair feels left out; Dan is unnerved watching one of Olivia's sex scenes with a former co-star.

Olivia says something she regrets during a talk show appearance and tries to keep Dan from finding out; Nate suspects that his grandfather will stop at nothing to get Trip elected to congress.

Jenny sets her sights on landing the hottest escort for Cotillion. Dan is upset when Olivia (HILARY DUFF) contemplates leaving school. All-girl French band PLASTISCINES performs.

Dan and Olivia sign up to write and star in a school play, based on an idea by Blair and directed by Vanessa.

Serena is put in an awkward position when Lily invites Tripp and Maureen to join them for dinner; Blair suspects her mother of keeping a big secret; Jenny gets even with Eric in the most cruel way.

Chuck wrestles with a past issue; A serious car accident rocks the Upper East Side; Dan and Vanessa try to navigate their complicated friendship.

Chuck tracks the woman he saw at his father's grave; Jenny agrees to help Damien; Nate and Serena get friendly.

Rufus and Lily grow suspect of Jenny's relationship with Damien. Chuck learns more about the woman who may or may not be his mother. Dan and Vanessa struggle through the awkwardness of dating other people.

Despite being grounded, Jenny continues to see Damien who tells Jenny that he wants to have sex with her. Lily thinks to tell the secret that she has up till now concealed, but after a call, she changes her mind. Dan and Vanessa explore the new development in their friendship. Chuck is forced to make an extremely difficult decision about his hotel. Meanwhile, Serena and Nate have a fight that is reminiscent of past events.

Chuck finds himself once again at odds with his uncle, Jack Bass. Eleanor puts Blair in charge of making sure her latest fashion show is a huge success with an important client. Rufus attempts to get Jenny back on track by volunteering to have her help with Eleanor's fashion show, but the opportunity takes a big turn for the worse when Jenny learns that Agnes will be one of the models.

Chuck and Blair are faced with the most difficult decision they have ever faced as a couple. Serena plans a surprise birthday party for Nate, but Jenny does her best to sabotage Serenas's efforts. Dan and Vanessa's new relationship hits a bump in the road.

Chuck offers to throw a wedding for a very pregnant Dorota who insists that she and Vanya have a traditional wedding before her parents arrive from Poland and find their daughter pregnant and without a husband. Dorota asks Blair and Chuck to be part of the ceremony and walk her down the aisle. Serena tells Nate she is having breakfast with the Humphreys when in reality she's secretly meeting up with Carter Baizen. Rufus discovers that Lily has been lying to him about her whereabouts.

When Lily's ex-husband, Dr. William van der Woodsen, shows up unexpectedly in Manhattan, Serena finally gets the reunion she has so desperately wanted with her father, but the circumstances turn out to be far from ideal. When Serena and Nate continue to have relationship issues, a scheming Jenny is more than happy to be a shoulder for Nate to lean on. Meanwhile, Dan finds out that he didn't get accepted into the Tisch writing program and Vanessa admits she may have been somewhat responsible.

Will's return to the Upper East Side continues to stir up problems for Serena, Lily and his long-standing rival, Rufus. Serena and Jenny's relationship is strained as a result of Jenny's deception. Blair spends time on the Columbia campus and realizes where she truly belongs. Dan learns that Vanessa has been keeping yet another secret from him.

When things get tense between Rufus and Will, Serena chooses to stand behind her father, while Rufus is made to feel like an outsider in his own family. Meanwhile, Jenny deliberately shares information with Will that may ultimately destroy Lily and Rufus' marriage. After many failed attempts, Chuck makes one last grand gesture to reconcile with Blair, hoping she will finally accept the fact that they are destined to be together.

Blair must decide whether to meet Chuck at the top of the Empire State Building or risk losing their future together. A Gossip Girl gossip bomb involving Dan explodes Serena and Nate's relationship. Dorota and Vanya welcome their baby. Jenny hits rock bottom. Georgina returns to the Upper East Side...and she has an agenda.

After having spent her Parisian summer alone (and in Serena's shadow), Blair hopes to change things when she meets a handsome young man who may be a real prince. But Serena has news that may only increase Blair's insecurity. Meanwhile, back in New York, Georgina and Dan's secret comes to light, and Nate meets a girl who seems refreshingly down to earth after a summer of Chuck Bass-rejects. And speaking of Chuck, he's still missing in action, which causes Lily to worry.

Blair is pursued by a handsome young man she suspects is part of Monaco's royal family. Chuck adjusts to a fresh start in Paris with a mysterious new woman, Eva.

On her first day at Columbia, Blair attempts to gain membership into an ultra-exclusive social club, Hamilton House, but she's in for a few big surprises. Serena begins to suspect that Juliet is intentionally sabotaging Serena's life and that it may have something to do with Nate. Rufus is worried about Dan and decides to take matters into his own hands.

Nate suspects that Juliet is keeping a big secret from him and decides to confront her. Blair schemes to undermine Chuck's newfound happiness. Dan finds himself torn between his feelings for Serena and Vanessa.

An anonymous Gossip Girl blast starts a very damaging rumor about one of Columbia's new students, Serena. On her path to greatness, Blair decides to take a class with a powerful businesswoman, Martha, who is guest-lecturing at Columbia, but a mysterious fellow student thwarts her plans to secure the prized position as Martha's assistant.

Although Blair made it perfectly clear that Little J was no longer welcome in Manhattan after what happened with Chuck, Jenny is tempted by a once-in-a-lifetime opportunity to meet Tim Gunn, which could be a game changer for her future. Meanwhile, Serena discovers something about her new boyfriend, Colin, that may put an end to their relationship just as it was getting good.

Blair is caught off-guard - and not in a good way - by a surprise guest at her birthday party. Having had enough of Chuck and Blair's games, Serena and Nate decide to plan an intervention.

Chuck and Blair decide it's in both their best interests to put the past behind them and end their vindictive games. Nate confronts Juliet after discovering a secret she has been keeping from everyone. Dan and Nate realize they both still have feelings for Serena.

Chuck hosts a "Saints and Sinners" masquerade party at the Empire Hotel. At the party, Dan and Nate don't know what to make of Serena's strange behavior and mixed messages. Blair sets her sights on becoming the new face of Anne Archibald's foundation for girls, but Anne is concerned that Blair's friendship with Chuck Bass may be problematic.

Chuck, Serena, Blair, Dan, Jenny and Eric find themselves faced with a crisis when a member of one of their families is hospitalized. Meanwhile, Nate attempts to help his parents, The Captain and Anne, put their complicated past behind them and reconcile.

Blair and Dan join forces to track down an MIA Juliet. Chuck begins to suspect Lily isn't telling him the full truth.

A former associate of Chuck's father, Russell Thorpe - along with his daughter Raina - returns to Manhattan with some unfinished business for our Upper East Siders. Serena and Chuck join forces against Lily. Blair realizes that her mother, Eleanor, may be her key to becoming a future CEO. Nate worries that his father, The Captain, is having a little too much fun and not taking his parole seriously.

Blair is ecstatic to land an internship at W Magazine, but the thrill quickly fades when she finds out that Dan has secured one of the coveted positions as well. Chuck may have finally met his match with Russell Thorpe - and his daughter Raina - back on the Upper East Side. Nate receives alarming news about his father's business prospects.

Blair enlists Nate's help to win over her high-strung boss, Epperly, at W Magazine. Damien stirs up more drama on the Upper East Side. Chuck finds himself torn between business and pleasure. Florence and the Machine performs an acoustic version of "Cosmic Love."

With Russell Thorpe poised for a takeover attempt of Bass Industries, Chuck makes one last-ditch effort to save his family's company. Blair is given a challenging assignment at W Magazine with the promise of a possible promotion. Serena struggles with her feelings for Ben.

It wouldn't be a proper Upper East Side party without some major Gossip Girl drama, and for Eric's 18th birthday celebration there is plenty to go around. Blair decides to speed up the time table on her career path to becoming a powerful woman, but ultimately stretches herself too thin. Serena is forced to choose between her family and Ben. Chuck and Lily's relationship remains icy in the aftermath of Lily's betrayal.

Ben's mother comes to town, forcing issues to the surface between Ben and Serena. Russell Thorpe is determined to destroy Chuck's family legacy, but he risks alienating his daughter, Raina, in the process.

As Lily awaits the consequences of her decision, William van der Woodsen, CeCe and Lily's sister, Carol, come into town to support her and be part of a Taschen photo shoot on "modern royalty" in which the Rhodes family is participating. Unbeknownst to Carol, who has always chosen to keep her daughter Charlie far away from the Upper East Side, Charlie has followed her to New York to meet Serena and the rest of the family. Blair has an epiphany about her future, and grapples with the knowledge of whom she's destined to be with.

Serena enlists Charlie to go undercover Gossip Girl-style to determine why Dan and Blair are spending so much time together, and what role an unexpected visitor is playing in their lives. With Nate's help, Raina decides to go on a search for her long-lost mother. Chuck's hopes about his legacy are dashed with the reveal of devastating information from the past.

Blair's dreams appear to be coming true, but Serena threatens to jeopardize it all by dredging up Blair's past. Charlie befriends Vanessa, who may or may not have a hidden agenda. Nate is torn between his relationship with Raina and a truth he must keep hidden out of loyalty to Chuck.

Charlie is finally starting to feel less like a fish-out-of-water with Serena and her friends, but complications present themselves when Charlie is invited to attend the Constance Billard alumni fundraiser. On the road to "happily ever after," Blair finds herself torn between the men in her life. Jack Bass' return to the Upper East Side sets off a chain of events that could end up destroying Chuck and those closest to him.

Season four wraps up with an explosive finale, including the return of Georgina Sparks and Constance Billard mean girls Kati and Is, a cameo by "Gossip Girl" author Cecily von Ziegesar, a performance by Airborne Toxic Event and, oh yeah, a few very juicy cliffhangers.

In a fashionable farewell to remember, our favorite Upper East Siders join forces for one last soiree; The identity of Gossip Girl is finally revealed.

Dan makes elaborate plans to impress Serena on their first official date; Jenny is invited to the infamous Blair Waldorf sleepover and finds herself in a high-stakes game of truth or dare; Lily discovers Eric missing from his treatment center, and seeks help from her ex-boyfriend, Rufus.

Although Blair made it perfectly clear that Little J was no longer welcome in Manhattan after what happened with Chuck, Jenny is tempted by a once-in-a-lifetime opportunity to meet Tim Gunn, which could be a game changer for her future. Meanwhile, Serena discovers something about her new boyfriend, Colin, that may put an end to their relationship just as it was getting good.

Blair sabotages her mother's show at Fashion Week; Dan starts hanging out with Chuck, and learns that a walk on the dark side always has risks.

Dan is torn between two girls when his childhood friend Vanessa returns home and declares her feelings for him

Serena realizes Aaron has kept a secret from her; Jenny and Agnes plan a guerilla fashion show; Blair baby-sits the daughter of a Yale donor.

Jenny sets her sights on landing the hottest escort for Cotillion. Dan is upset when Olivia (HILARY DUFF) contemplates leaving school. All-girl French band PLASTISCINES performs.

Jenny befriends a model, and is encouraged to explore her wild side; Serena is attracted to an artist, Aaron Rose.

Serena throws Jenny a party for her 16th birthday, but things get out of control when Poppy Lifton turns the small gathering into a huge social event.

Blair returns to school after losing Queen Bee status; Serena's not fond of living with her future stepbrother, Chuck.

Despite being grounded, Jenny continues to see Damien who tells Jenny that he wants to have sex with her. Lily thinks to tell the secret that she has up till now concealed, but after a call, she changes her mind. Dan and Vanessa explore the new development in their friendship. Chuck is forced to make an extremely difficult decision about his hotel. Meanwhile, Serena and Nate have a fight that is reminiscent of past events.