It's the day right after the Kiss on the Lips party and Serena receives a cold reception from her former best friend Blair. Blair reveals that she knows that Serena and Nate slept together, before Serena mysteriously went to boarding school. Then Serena decides to take Dan to Chuck's fundraiser brunch at The Palace. Meanwhile little Jenny asks Blair for advice, and Blair realizes that she maybe gains something by allowing Jenny into her inner circle.

It's Ivy week for the Upper East Side teens of Constance Billiard and St. Jude's and the visiting representatives' arrival brings more than just college applications. Cut-throat rivalry is at its sharpest this week as the students compete for prestigious positions. Blair discovers a shocking but juicy secret about Serena and plots to drop the bomb at the best possible moment. Dan is sure that landing the coveted usher position with the Dartmouth rep will either make or break his future at the school. Unfortunately, it's Nate who nabs the position, despite total disinterest in the school. Meanwhile, Jenny gets closer to Serena's younger brother Eric and Rufus asks Lily for a favor.

Blair gets excited when her mother, Eleanor, chooses her to be the new face of her clothing line. However, Blair's happiness turns quickly into feelings of betrayal and jealousy when Serena takes her spotlight and Blair finds herself back in Serena's shadow. Meanwhile, Serena and Dan remember once again that they come from two very different worlds. Also, Nate and Chuck do a boys weekend to blow off steam after Ivy Week ends.

Dan finds himself between two girls when his childhood friend, Vanessa, returns to N.Y. and declares her feelings for him, just as he and Serena are trying to figure out what they mean to each other. At the masked ball, Blair sends Nate on a scavenger hunt, but Nate is distracted by his feelings for Serena. Although Blair said that outsiders were not welcome to the party, a disguised Jenny and Dan sneak into the ball. Finally, Lily asks Rufus to accompany her to an Eleanor Waldorf event only to make Bart Bass jealous.

Serena and Dan finally accept that they are crazy about each other, despite that they come from polar opposite worlds. Chuck thinks of investing in a club trying to make his father Bart Bass proud of him. Nate confronts his father, about the drugs he found in his house but he denies having a problem. Jenny discovers a secret that her parents have been keeping from her. Finally, Blair is devastated by Nate's actions when Jenny reveals that Nate kissed her by accident thinking she was Serena.

Blair is feeling heartbroken and guilty by the current state of her relationship with Nate and her recent indiscretion. But she manages to put on a happy face for her 17th birthday party and attempts to hide her feelings from her friends. Hoping that Serena and Vanessa can bond, Dan takes Vanessa to Blair's birthday party. Jenny brings her mother home as a surprise, but Rufus isn't ready to forgive and forget. Finally, Nate's parents ask him to make a huge sacrifice to save his father's business.

Dan invites Serena and her family to spend the holiday with his family, creating an uncomfortable situation for Rufus and Lily. The children are unaware of their complicated romantic past. Meanwhile, Blair's freaks out when she learns that her father isn't coming home for Thanksgiving. Nate spends the holiday with his family, but their awkward dinner quickly goes from bad to worse.

Blair's father, Harold, comes home for the holidays with an unexpected guest. Blair cannot hide her disappointment and makes a plan to get rid of Roman forever. Jenny and Vanessa help Serena get the best Christmas present ever for Dan, who has a surprise of his own for Serena. Rufus refuses to remain the understanding husband any longer after Alison's former lover sends a letter to the house.

Gossip Girl reports that Serena van der Woodsen was seen buying pregnancy tests. Of course, on the Upper East Side, the truth is often even juicier and more scandalous than the gossip. Nate finds out about Blair and Chuck's affair. And when everyone else finds out what happened Blair's life comes crashing down. Meanwhile, Dan struggles to tell Serena those three special words.

Blair is over the moon that she is dating royalty and has every intention of becoming a royal herself, but a scheming Chuck has other plans for Blair and her new love, Marcus, when he introduces Blair to Marcus' stepmother who happens to be Catherine. Meanwhile, Nate learns the downside to having an affair with Catherine when he keeps getting caught in his lies and learns his family has gone bankrupt due to his father jumping bail.

In a humorous twist, Blair questions the lack of passion in her relationship with Marcus, while at the same time Chuck appears to have lost his "passion" for any woman other than Blair. Meanwhile, Nate struggles between his feelings for Vanessa and his more-complicated-by-the-day relationship with Catherine. Jenny risks losing her internship when Eleanor catches Jenny critiquing one of the Eleanor Waldorf designs.

In the midst of Fashion Week, a furious Blair learns that her mother, Eleanor, at the suggestion of her protege Jenny, has given Serena and her new socialite friend, Poppy Lifton, front row seats to the Eleanor Waldorf show. Hurt once again by Serena's popularity and her mother's betrayal, Blair decides to sabotage the show. Meanwhile, Dan starts hanging out with Chuck, but a walk on the dark side always has its risks and Dan learns that the hard way. Lily learns a secret that her new husband, Bart, has been keeping from her.

After Blair and Serena get into a catfight, Serena decides to get even with Blair, who has always dreamed of attending Yale, by ditching her plans to visit Brown, and instead accepting the Dean of Yale's personal invitation to visit the school. After discovering that none of his recommendation letters for Yale were ever submitted, Dan frantically tries to figure out a way to salvage his chances of getting into the school. While on the Yale campus, Chuck is kidnapped by a group of Skull and Bones members and Nate hooks up with a co-ed.

Jenny has a new young model friend, named Agnes, who encourages Jenny to explore her wild side, and also to confront Eleanor Waldorf who is planning to steal Jenny's designs in order to pass them off as her own. Meanwhile, Serena and Dan attend Rufus' latest art opening as friends, but then Serena meets an artist, named Aaron Rose, and the evening gets a little uncomfortable for Dan. Elsewhere, Blair attempts to seduce Chuck, but he proves to be tougher than she ever imagined. Also, Jenny begins to have a mutual feelings with Nate as he's staying with her, Dan, and Rufus while searching for a place to live.

Blair sets out on a mission to break up her mother and Cyrus Rose, her new man. Jenny moves in with Agnes as the two continue with their plans for their own fashion line. As Serena continues to fall for Aaron, she learns something that may derail their relationship forever while Dan interviews Bart Bass for an article for New York Magazine.

It's Thanksgiving time and Blair is offended when her Mom's new man hijacks her Thanksgiving traditions. Lily attempts to strengthen the frail bond between Rufus and Jenny. Eric discovers a secret about Bart. Vanessa and Chuck help Nate deal with his father.

The entire Upper East Side of Manhattan is rocked when Bart Bass dies suddenly in a limo accident. Serena and Eric take the news very calmly while Lily has a troubling time despite her mother, Cece's, awkward attempts to comfort her. Chuck begins to blame Lily for his father's death and threatens to reveal a secret that Bart found on her before his accident. Meanwhile, Blair's mother, Eleanor, prepares for her latest marriage to Aaron's father Cyrus.

Serena returns from her trip to Spain with Poppy and Gabriel. Blair makes a secret deal with Nate's grandfather. Dan takes a job to earn money for college.

Gossip Girl decides to liven things up at the Constance Billard and St. Jude’s graduation by sending out a shocking and damaging email blast in the midst of the commencement ceremony, stirring Serena to come up with a plan of attack. The Mean Girls challenge Jenny to throw her hat in the ring to succeed Blair as Queen Bee next year. Lily and Rufus struggle to repair their relationship after Lily’s betrayal. As for the cliffhangers, Blair and Chuck finally… and Serena is shocked by… and Georgina decides to… and Dan, Nate, and Vanessa unknowingly…. Jenny and Eric do something they might end up regretting.

It wouldn’t be Thanksgiving on the Upper East Side if there wasn’t a serving or two of some major drama for the holiday. Blair suspects her mom has been keeping a big secret from her, but it turns out to be something else entirely. Vanessa is supposed to spend Thanksgiving with her parents, but has a fight with her mom and shows up on Dan’s doorstep. Rufus learns that Lily has been lying to him about her mother, Cece. Chuck tells Nate that he has some potentially damaging information about one of their friends. Jenny learns that Eric was behind her very public embarrassment at Cotillion and can’t pass up a chance to get even. Serena is put in a very awkward position when her mother invites Trip and Maureen to join them for Thanksgiving dinner.

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 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.

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.

Blair and Serena spent their summer living it up in the belly of the beast: Paris, France. But where there's Paris there's bound to be boutique, Balenciaga, and of course, boy trouble. Unaware of Chuck's shooting in Prague, Blair struggles to forget him; things take a turn, however, when Chuck mysteriously shows up in Paris with a foreign stunning blonde at his arm. Meanwhile Serena contemplates which of her long-time beaus could be the one for her: Dan or Nate? Even on the Upper East Side drama erupts as Dan figures out the baby mama drama with Georgina, and Nate realizes something about himself when he meets fellow Columbia student, the intriguing Juliet.

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.

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.

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.

The episode continues from the early events of the Constance Alumni event. Georgina Sparks turns up at the event looking for trouble. Serena and Vanessa reluctantly join forces to find Dan and Charlie, who does not take Dan's rejection of her well. Blair must make a choice between the men in her life when her life is in danger by Russell.

Serena loves her new job in Hollywood, but makes a costly misstep when she tries to impress her boss. Chuck and Nate arrive in Los Angeles as the last stop of their Lost Summer trip, joining Serena at a glamorous Hollywood Hills party, where Nate meets a sexy older woman. Blair and Louis return from Monaco and begin planning their royal wedding, but when Louis refuses to stand up to his family and support Blair’s choices, his weakness threatens their relationship. A magazine is planning to run an excerpt of Dan’s book until an unlikely ally steps in to help him kill the story.

In the midst of celebrating Yom Kippur with family and friends, Blair and Louis find themselves in a power struggle with Louis' family. Serena's boss puts Serena in the awkward position of choosing between her new job and her relationship with Dan. Diana prepares to debut the New York Spectator, but an unfortunate last-minute surprise delays the launch and Diana expects Nate to do whatever it takes to save the day.

The much-anticipated 100th episode will open with a musical dream sequence featuring Serena, Blair and all the men in their lives. Also, while Chuck wrestles with the reality that Blair is about to walk down the aisle with Prince Louis, the return of Georgina Sparks might make the royal affair a royal disaster.

Blair must make a difficult decision about her future, the consequences of which could hurt those she loves most. Serena takes the blame for an incident with Gossip Girl in order to protect someone she loves.. Georgina smells the scent of scandal and decides to follow its trail.

Blair enlists Serena to be her stand-in at an important meeting when Blair finds herself needing to be in two places at the same time. Meanwhile, Ivy and Lola team up to help Chuck with a personal vendetta, and Nate makes a decision about the future with Diana Payne.

When Gossip Girl goes after Blair as she’s never done before, Serena admits she may have unintentionally played an important role in Blair’s latest nightmare. Meanwhile, Nate invites Lola to move in with him, and Lily must make a big decision about the future of her marriage. Finally, by episode’s end, Blair will make a choice between the two men in her life…will it be Chuck or will it be Dan?

Serena volunteers to help Dan find a new place to live but their time together brings up unexpected emotions.

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