Ryan Atwood is a troubled, 16-year-old kid living in the rough, crime-ridden neighborhood of Chino located in San Bernadino, California, who gets thrown out of his own house by his alcoholic and neglectful mother and her abusive, alcoholic boyfriend after Ryan gets into trouble with the law when his self-destructive older brother, Trey, implicates him in the theft of a car. Ryan is appointed, Sanford 'Sandy' Cohen, a public defender, who takes the homeless youth to his house in the posh and picturesque neighborhood of Newport Beach, Orange County, (the OC) and lets Ryan stay in the guest house against the protests from Sandy's wife Kristin and their bumbling and socially handicapped son Seth. Ryan forms a bond with Marissa Cooper, a friendly, but similarly emotionally troubled teenage girl living next door who introduces Ryan to the world of beach parties and life of the idle rich in Newport Beach. But Ryan's feelings for Marissia are hampered by Marissa's egotistical jock boyfriend, ... Written by Anonymous

When his mother disappears and faced with the prospect of life in a group home, Ryan decides to run away from Newport, but Seth and Marissa convince him to stay and hide in a vacant building project. Meanwhile, Jimmy discusses his recent financial woes with Kirsten, and she offers a solution. After the jealous Luke witnesses a close encounter between Marissa and Ryan, he confronts Ryan and a fight breaks loose in the house where their quarrel accidentally starts a fire. Ryan nearly dies in the flames, until surprisingly Luke returns and saves Ryan's life, which unfortunately reveals Ryan's continuing presence in Newport leading to both him and Luke getting arrested for arson. Written by Anonymous

Ryan has a difficult stay in a Juvenile Hall prison for the arson charge. Seth makes Kirsten aware of his anger over Ryan's situation, and Kirsten makes a compromise to bail Ryan out of jail to stay with them, temporary. Later, Ryan's mother, Dawn, makes a surprise visit to Newport, and things don't go quite as she and Ryan may have planned due to her constant drinking. Meanwhile, the monetary secret involving Julie, Jimmy, Kirsten and Sandy comes to a head when Sandy finds out of Jimmy's financial problems about the money investments he lost and unwisely 'borrowed' without permission from his clients bank accounts to cover it up and lost that money too, and of Kristen's lending their money to help Jimmy which brings out more jealousy in Sandy for he's aware of Kristen and Jimmy's romantic past. Written by Anonymous

During rehearsals for Newport Beach's annual Cotillion Ball, Ryan continues to pursue Marissa and asks her to be his dancing partner, while a continuing jealous Luke tries to break them up. Seth as eyes for the new girl in town, Anna Stern, but becomes torn over his feelings for Summer Roberts, the outgoing socialite he's had a crush on for years. Meanwhile, Sandy becomes upset over Kristen's loan to Jimmy for his financial problems which finally come to light at the ball when one business client decks him in the face after learning that Jimmy lost all of their money. Written by Anonymous

Ryan takes a job at the Crab Shack diner where a co-worker, named Donnie, might mean bad news for the Newport kids when he takes Ryan and Seth out to party queen Holly Fischer's parties where drugs and alcohol flow freely. Ryan asks Marissa out on a date, and when Luke again tries to intervene, Donnie decides to take matters in his own hands when he tries to starve off Luke... with a gun. Meanwhile, Sandy attempts to help Jimmy sort out his life, and gives him some bad news that be may go to jail for his unauthorized loans to cover his tracks. Also, Julie reveals a long-held secret to Kirsten about her past. Written by Anonymous

Kirsten's uptight father, Caleb Nichol, comes for a visit along with his new girlfriend, Gabrielle, a 24-year-old model. Caleb does not hesitate to speak his mind and immediately angers both Sandy and Ryan, and browbeats Seth, with constant criticism with their backgrounds, while Gabrielle makes a move on Ryan. Kirsten finds her job at Caleb's company, Newport Group, in jeopardy, while Sandy considers making a change. Meanwhile, Luke approaches Marissa and tells her that he wants a second chance with her, much to Ryan's disappointment. Also, Summer makes the moves on Seth, who wonders if her feelings are real or if she just using him. Written by Anonymous

Ryan, Seth, Marissa and Summer plan an end-of-summer trip down to Tijuana, Mexico (aka: the TJ). Luke wants to tag along with them to try to get back together with Marissa, but she later changes her mind about him when she catches Luke making the moves on Holly Fischer. Back in Newport, Jimmy has plans of his own to get out of his financial and legal problems, which don't sit well with Marissa or Julie. Sandy gets a new job at a large prestigious law firm, which Kirsten can't understand why. Written by Anonymous

While Marissa is in a hospital in Newport recovering from her near-fatal drug overdose in Mexico, Julie unfairly blames Ryan for her condition and forbids him from seeing Marissa, who does not appreciate the help. Meanwhile, Sandy starts his new job, but finds himself surprised by the case work. Kirsten finds herself surprised by Sandy's new co-worker, the attractive Rachel. Also, Ryan enrolls at his new school, with conditions after his past life in Chino is revealed. Ryan and Sandy then stage an intervention for Julie about her handling of everything in which she lets Marissa stay with Jimmy who moves out and rents a small apartment for himself. Written by Anonymous

At the opening day of the new school year, Ryan doesn't feel like he fits in at his new school of Harbor High, and Luke doesn't make the situation any better when he and his jock friends continue to bully and harass both him and Seth, who doesn't like being at school any more than Ryan. Meanwhile, Sandy accepts a case at his new job, a case that will test his relationship with Kirsten and her father Caleb. Anna and Seth hatch a plan to make Seth feel better with his current situation. Also, Ryan and Luke confront Marissa and force her to choose one of them.

Having chose Ryan over Luke, Marissa wants to make plans for their first romantic date together, while Ryan does not know how to behave for his first date with Marissa. Seth takes matters into his own hands involving getting to like Summer, but gets taken in with Anna whom also develops feelings for him too. Meanwhile, Ryan finds Caleb with another woman, that being Julie Cooper, while Sandy continues to resist temptation with his co-worker Rachel.

On Thanksgiving Day, Ryan ventures to his hometown in Chino to help his imprisoned brother, Trey, with some business he has, while Marissa tags along with Ryan to get a look at the neighborhood where he was born and raised, but it brings out some bad situations and unpleasant trips down memory lane for Ryan. Back in Newport, Kristen invites Caleb and Julie over for Thanksgiving dinner where Seth takes the player role of playing both Summer and Anna. But he does not play it well, leading to both of the girls running into each other and learning about Seth's two-timing act. Written by Anonymous

Ryan learns more about Luke when they're paired for a school history project which is that Luke isn't the macho tough guy he puts out to his friends, but he is quite a nice person with a perfect home life. But things take a sudden turn when Ryan and Luke stumble upon a secret of Luke's father's homosexuality. The next day, the news of Luke's father is the talk of the whole school and the town resulting in negative reactions to Luke from his friends, in which he blames Ryan who denies telling anyone about his father being gay. Meanwhile, Kristen continues to avoid Jimmy over their disastrous Thanksgiving dinner encounter, while Sandy has some advice for Jimmy over his legal problems which doesn't set well with Julie over selling their house to pay off the money he lost.

Ryan is officially introduced to the bi-religious holiday of 'Chrismukkah', thanks to Seth who has set this up for his parents; the Catholic Kristin and the Jewish Sandy. At the same time, Seth insists he has two Godly forces helping him as he continues to play both Summer and Anna by claiming he has chosen the other. Meanwhile, Marissa slides more into depression and debauchery over her family life problems and gets arrested for shoplifting with Ryan. It gets worse when she gets drunk at Seth's 'Chrismukkah' party and nearly gets arrested for drunk driving while Ryan covers for her, and afterwords gets into a fight with her saying she can't do this to herself anymore. Kirsten does something that could cost her more than just her job over speaking out of her father Caleb's shady business deals. Summer and Anna find out about Seth's playing of them and decide to give him a 'very special gift' to make him choose which one he wants to be with. Written by Anonymous

Kirsten's outgoing and spoiled younger sister Hailey Nichol, notorious for not doing anything with her life, returns home and asks to stay for New Year's Eve. Although getting along fine with everyone, she shows her true colors when she throws a destructive New Year's Eve party at the house when Sandy and Kristen are out and locks both Ryan and Seth in the guest house. Meanwhile, Sandy and Kirsten get lost while traveling to a restaurant for dinner, and, thinking they're in a rut, find themselves out of their environment at a swingers house party. The mysterious Oliver Trask, a charming young teenager Marissa met in her therapist's waiting room, takes advantage of a mild quarrel between her and Ryan to cast his spell on her and invite her and her friends to his New Year's Eve party at his parents' posh penthouse. Also there in attendance are Summer and Anna who talk about Seth and decide to find him to make him choose which one of them he wants to be with. Written by Jim

Hailey discovers that she isn't welcome into the Cohen household as much as she thought due to her continuing irresponsible and brash lifestyle and personality leading to a fight with Kristen and Sandy over her living arrangements. Meanwhile, Oliver continues to charm Marissa and throws his weight around by inviting her, Ryan, Seth, Summer, Anna and Luke to a rock concert where the band Rooney is playing. There, Luke makes some new friends with the band fans, while Seth and Anna debate on telling Summer about their newfound romantic status. But trouble brews for Ryan when he becomes suspicious on Oliver's well being and catches him in a compromising position involving a suspected drug dealer in the parking lot.

Oliver plans a new trip for the group by inviting them to Palm Springs for the weekend to play golf and travel around. But things don't go well for everyone, except for Oliver when his erratic behavior begins showing itself to Ryan and Luke, but Marissa brushes it off as just playful behavior. But when Ryan tries to tell Marissa that Oliver is not what he appears to be, he gets left out in the cold. Summer tries to plant herself into a friendship with Seth and Anna leading to a competition of wills over both of them. Meanwhile in Newport, Jimmy and Sandy decide to go into business together of opening their own restaurant while Caleb and Julie return from a two-month vacation in Europe. Also, Kirsten and Hailey continue to butt heads over Hailey's irresponsible behavior leading her to finally move out of the Cohen household. Written by Anonymous

Ryan continues to become suspicious of Oliver when he suddenly transfers to Harbor High and begins making plans of his own with Marissa. But Ryan's attempts to try to expose Oliver of the person that he is, gets met with negative approval from everyone, leading to a familiar situation. Summer shows off her new boyfriend, Danny, to Seth and Anna who correctly think that Summer is just showing off to satisfy her own ego. Meanwhile, Sandy and Jimmy prepare to sign the lease papers to build their own seafood restaurant, the Lighthouse. But Jimmy doesn't know if he's ready for this new business venture. Written by Anonymous

Ryan finds himself truly out in the cold when he's suspended from school, shunned by Marissa, and even scrutinized by the Cohens, all of whom refuse to believe Ryan's claims that that Oliver is a dangerous sociopath and obsessed with Marissa. Ironically, the only person who believes Ryan is Luke, who agrees to help Ryan make a background check on Oliver to find any dirt on him. But when Luke reveals evidence to Marissa, and then Sandy, that some of Oliver's references from his old school are false, they refuse to believe Luke, especially after learning that he's been talking with Ryan. Meanwhile, Jimmy thinks his past will impair his ability to work in the business field again. Seth continues dating Anna who thinks Summer's presence around them is not a good thing. Things come to a head when Oliver begins losing his bland, self-control to lie when Marissa comes by to his penthouse to tell him that she not interested in a relationship with him. Then, he really loses it and Marissa sees... Written by Anonymous

On Valentine's Day, everyone is preparing for the Valentine's singles benefit dance. Luke has a new crush: that being Marissa's mother Julie. Meanwhile, Sandy gives Seth some sex advice over his dating of Summer. Theresa Diaz, an old friend Ryan's, shows up in town as part of the catering services for the benefit, which forces Marissa to lay her feelings on the table that her breakup with Ryan may have been a mistake. Also, Seth and Summer take their friendship to another level. Written by Anonymous

Ryan and Marissa begins their lives as just friends in the aftermath of everything that has happened. But they soon find out that it is not as easy as it looks. Things take another turn when Ryan's former flame, Theresa Diaz, show up in Newport to work as a waitress for a special gathering and wants to try to reconcile with him. Meanwhile, Julie and Luke begin having a passionate affair behind everyones backs, while Seth and Summer decide to declare their love for each other. Written by Anonymous

When Anna announces that she is leaving Newport to go back to her home in Pittsburgh, Seth feels guilt-ridden for he way he treated her. Meanwhile, trouble brews for both Caleb and Kristen at the Newport Group over their legal funds, and Sandy tries to help them out. Luke finds that his secret romance with Julie is getting harder to keep a secret. Also, Theresa brings a lot of trouble for herself and Ryan from Chino when her boyfriend, Eddie, shows up, making Ryan slightly jealous and worried about Theresa's well being. Written by Anonymous

When Marissa and Summer run into Grady Bridges, the star of Summer's favorite TV series The Valley, he invites them and their friends to a party in Los Angeles and they accept. Meanwhile, Ryan and Seth discover the romantic connection between Luke and Marissa's mother in which Ryan persuades Luke to break it off before Marissa finds out. During the L.A. party, Grady tries to woo Summer away from Seth, who gets an eyeful of a wealthy socialite lady, while Ryan and Marissa run into Hailey Nichol whom is now working as a stripper and they call upon Jimmy for help. Back in Newport, Sandy and Jimmy approach Caleb to ask for his help to arrange a get-together for some of Newport Group's wealthy business elite to get funds to open their own restaurant. Written by Anonymous

Sandy's overbearing and obnoxious mother, Sofia the Nana Cohen, arrives in Newport Beach to celebrate Passover, but she also brings not only her unattainable attitude, but some bad news that she's dying from cancer. Meanwhile, Ryan searches for Marissa who has gone missing after inadvertently learning about her mother and Luke, and Ryan finds her in the most unexpected of places: at Theresa's house in Chino. Also, Summer tries to impress the Nana by knowing the traditions of Judeaisum, while Jimmy and Hailey take a step forward with their own newfound romance. Written by Anonymous

Jimmy and Sandy run into a roadblock in their effort to re-open the Balboa Lighthouse restaurant when some investors withdraw their funds and it's revealed that they were Jimmy's former business clients whom he lost all of their money. Meanwhile, Summer and Seth take it upon themselves to finally make Marissa feel more at home at Jimmy's apartment. Things take another when when Caleb makes a marriage proposal to Julie, which sparks anger and a feeling of betrayal for Luke who gets behind the wheel of his car and has a near-fatal accident. Also, Marissa, and Sandy and Jimmy each strike deals with Caleb in which he forces Marissa to live with him and Julie after they are married in exchange for helping Jimmy and Sandy with their business adventure. Written by Anonymous

Everyone is still reacting to the surprise engagement of Julie and Caleb. Kirsten is shocked, and a little burdened to find she's been asked to be Julie's Maid of Honor. Kirsten and Marissa end up in charge of throwing Julie's wedding shower, and Marissa invites an unwanted guest: Julie's estranged sister whom does not approve of her upcoming wedding whom she suspects that it's purely for money. Meanwhile, Theresa calls Sandy for help when she runs away from Chino and tries to avoid Ryan. Jimmy and Hailey continue their romance, and Seth awkwardly meets Summer's father. But Seth's lack of social skills make Dr. Roberts disapprove of him. Written by Anonymous

Sandy and Jimmy, along with Ryan and Seth, set out to Las Vegas for Caleb's bachelor party. But the Cohen men soon learn that Caleb has double-crossed them over financing their restaurant, while the boys get themselves into trouble with some angry gamblers. Meanwhile, Kirsten throws a bachelorette party for Julie at the house where Hailey quarrels with Julie, and Theresa finds comfort with Marissia over her recent setbacks. Written by Nick

Julie and Caleb marry, and Marissa moves into their new mansion. Meanwhile Theresa asks Ryan to move to Chino with her to look after the yet to be born baby. Upon finding out about Ryan leaving, Seth decides to leave via his yacht abandoning Summer and his parents. Written by Charlie