Twins Brandon and Brenda begin school at trendy West Beverly High after moving from Minnesota. Brandon joins the newspaper and meets Andrea Zuckerman, the intelligent and devoted editor. Brenda is befriended by snobbish Kelly, who picks her as a chemistry lab partner to avoid being paired with a fat girl. A rich but reclusive girl invites the entire school (except the freshmen) to a party at her house, complete with a live rock band. Freshmen David and Scott crash the party, and the drunken Steve asks David to drive him home. David accidentally damages the car, prompting Steve to begin a frantic search for the culprit. Brandon connects with the hostess, Marianne, and goes on a date with her. He insinuates that they slept together, prompting rumors to fly at school. Andrea is disappointed in him. Brandon clears the air about Marianne over the campus radio station. He follows Andrea home to explain himself, and discovers that she lives out of district. Brenda and her friends get fake IDs

Brandon meets Dylan McKay, a mysterious loner who stops some jocks from harassing Scott in tech class. Dylan takes Brandon surfing and introduces him to his friends, including a troubled young woman named Sarah.

Brenda goes on several shopping trips with Kelly and Tiffany, Kelly's best friend from junior high school. Brenda cannot afford the merchandise, and considers stealing because she is envious of her classmates' wardrobes.

Sheryl, Brandon's old girlfriend from Minneapolis, stays with the Walshes for the weekend. A concerned Cindy asks Jim to have a talk with Brandon. Before he gets around to it, Sheryl spends the night in Brandon's room. Sheryl seems obsessed with wealth and fame, and takes a liking to Dylan and his Porsche. Brandon believes that Dylan is hitting on Sheryl and punches him. Brandon is stunned to learn that he was not the first guy to sleep with Sheryl. Sheryl's mother calls Cindy and reveals that her daughter ran away following a fight with her stepfather. Brenda babysits for her handsome algebra teacher, with "help" from Kelly and Donna. She no longer finds him appealing after watching his wife push him around.

Jim encourages Brandon to try out for the basketball team. Steve, unaware that he is terrible, is bitter about being cut from the team. He tells Brandon that several of the players are ringers brought in from out of district to help the team win a championship.

Brandon is getting a C in American History because of the teacher's unreasonable grade curve, in which 80 percent of the students receive C's regardless of their marks. Steve scores an A on every test because he obtains copies of the exams beforehand. Feeling pressure from Jim about his grades, Brandon cheats on a quiz. Andrea is furious, particularly when her grades slip as a result. Brandon is faced with a moral dilemma when Steve offers him a copy of the midterm. Brenda tries to dye her hair blonde in the hopes of impressing Dylan, but winds up looking like a clown. Dylan flirts with Brenda and takes her to a stylist to repair the damage.

Brenda is mesmerized by Kelly's hip and glamorous mother Jackie, a former model. Kelly insists that her mother is not all that she appears to be. Jackie is a recovering addict, and begins hitting the bottle again after her boyfriend dumps her. Cindy is hurt when Brenda initially fails to ask her to be in a mother-daughter fashion show. They eventually agree to appear, and are joined by Andrea, who draws raves. Jackie attempts to emcee the show while high on cocaine. She becomes disoriented and disrupts the show with a rambling tirade. Kelly convinces her to check into rehab. Kelly gains new respect for David when he gives her the fashion show tape to save Jackie from embarrassment. Jim becomes addicted to his new keyboard.

The Walshes celebrate their seventeenth anniversary, but Cindy feels dissatisfied because Jim is neglecting her for his work. She has a chance meeting with old flame Glen, a talented artist. The two spend a lot of time together, and share a kiss after Glen's opening. Brandon and Brenda take part in a college study on twins, but are distracted by their parents' marital problems. David becomes the new campus DJ after Steve chokes in his tryout.

Brenda becomes a trainee for a teen crisis hotline, although Andrea questions her devotion. Brenda violates the rules by taking a call after hours. The caller is a date rape victim, who suffers the same fate on three consecutive nights. Brenda is desperate to learn the girl's identity and help her. Brandon believes that a masseuse has a romantic interest in him. He also dodges a freshman admirer, who similarly gives the cold shoulder to Scott.

Brenda and Dylan continue their flirtation, and she accidentally catches him in the shower. They go out alone when Brandon has to stay home sick. Dylan loses his cool after a confrontation with his father. Brenda consoles him, and they end up kissing. Jim objects to the relationship because Dylan's father is considered ruthless and crooked. Brenda is prepared to go all the way, and is crushed when Dylan stands her up. He later explains that he had to move because his father skipped the country to avoid an indictment. Steve tries to make a pass at the speaker for a sex education assembly. She reveals that she has AIDS. Her speech prompts Brenda to slow things down with Dylan.

Brenda goads Brandon into taking her to a party at Donna's house. He voices his objections to alcohol, but Steve spikes his drink. He decides to go along with it so that he won't appear ""uncool."" Kelly gets drunk and sleeps with Steve. Cindy catches Brenda with alcohol on her breath, but Brandon gets by unscathed. Jim and Cindy attend a weekend retreat, where they are forced to spend all their time with an overly friendly couple. Brenda convinces Brandon to throw a party, but they agree not to drink. Word of the party spreads, and it quickly gets out of hand. Brandon drinks heavily and kisses a stunned Andrea. Kelly dances with the lovestruck David to avoid Steve's advances. Brandon tries to drive to the store and smashes his car. He is arrested for drunk driving. Dylan takes him to an AA meeting and reveals that he is an alcoholic.

Brandon meets senior Melissa Coolidge on the school lawn during lunch. He makes a date with her, and learns that she is the mother of an infant son, Joey. Brandon is forced into emergency babysitting duty while Melissa has an interview with Harvard. Jim and Cindy are unavailable, but Steve helps Brandon through the afternoon. Melissa's interview does not go well, and she becomes frustrated with her life. She fears that she may have to give up her son, but Cindy calms her with a heart-to-heart talk. Brenda and Kelly win skydiving lessons from a radio contest.

Brenda invites Kelly, Donna and Andrea over for a "night of female bonding." They are having a good time until Kelly's friend Amanda shows up. She insults everyone and decides to turn the girls against each other. As part of a "game" about secrets, Amanda bullies Kelly into describing her first sexual encounter, in which she was humiliated by the football captain. After Brenda recalls stealing a Minnesota friend's boyfriend, Kelly admits that she tried to hit on Dylan. The girls eventually make up, and Brenda and Kelly vow to never let a man come between them. Amanda's behavior is attributed to a diet pill addiction. The girls catch David and Scott lurking outside the window and taking pictures of them. Brandon and Steve are denied entry to a club, but hook up with two girls. They steal Steve's Corvette, but he doesn't press charges (and pays their traffic ticket) because he foolishly thinks that he and Brandon still have a chance with them.

The Walshes agree to let their maid's extremely intelligent "niece," Karla, use their address to enroll at West Beverly. Brandon falls hard for her, but doesn't understand why everyone seems opposed to their relationship. Carla reveals that she witnessed a drive-by shooting that claimed the life of a four-year-old; she had moved in with Anna while waiting to testify, with protection from the D.A. Carla returns to her family after one of the killers confesses. Jim and Cindy organize a soiree for his new client, a sportswear designer. Dylan, Steve and the girls receive free clothing. David wants MC Hammer to perform at the school dance.

David invites Steve, Kelly and Donna to his grandparents' luxurious Palm Springs home for President's Day weekend. He is embarrassed to find that his grandparents, who he believed were on a cruise, are actually at home. David meets a strange girl at a gas station and asks her over to the house. She brings friends for Steve, who is still trying to win back Kelly. Brenda plans to spend the weekend with Dylan, but cannot remember the name of his hotel. She loses her wallet and spends the night in a linen closet. She finally makes it to the hotel, only to find Dylan hanging out with another girl. David's grandparents give the teens advice about romance, and help Brenda and Dylan. Brandon befriends a young customer at the Peach Pit, but later catches him trying to steal cash. The boy reveals that his family is homeless.