Jennifer develops her first major crush on science lab partner Tim Higgins, the handsome star pitcher of the school baseball team. When Tim comes over to work on their science project, Jennifer is thrilled, but also embarrassed by his open admiration of her academic talents. Believing the adage that boys never like girls who are smarter than they are, she decided the way to keep Tim interested is to play dumb.

Alex realizes he must make Ellen aware of his feelings, but she is on a train on her way to marry another man, so he takes drastic measures to stop the wedding. The usually cool Alex decides he must let down his defenses or lose the girl he loves.

Alex implements a fail-proof, and extremely unromantic, method of meeting the girl of his dreams: He picks her from pictures in the freshman directory. His selection, Tricia, seems to fit his requirements perfectly, but his plan goes off-track when he is strongly attracted to her roommate, Ellen. Ellen and Alex dislike each other instantly, and though he can't figure out why, he finds himself thinking about her constantly.

Mallory brings home her new boyfriend, Nick, a Rambo-type environmental artist, to meet her family, but Steven and Elyse are shocked by his crude appearance and gruff manner.

While Steven and Elyse are away on vacation, the Keaton house becomes a hotel for the weekend after Mallory accidentally crashes her parents' car into a telephone pole and the kids need to raise money for auto repairs. A lot of people are in town for the Leland homecoming game, so Alex decides to take advantage of the situation and rent out rooms but suddenly he's swamped with renters and the house looks like a three-ring circus.

When Alex takes diet pills for a lift during mid-terms, his dependency level increases daily. Alex is studying for several tests and convinces Mallory to obtain diet pills to help him stay awake. At his hyperness and irritability increase, so does his dependency on the pills. When he finally gets so desperate that he threatens Mallory to get more drugs, she becomes worried that he is headed for a ""crash landing"".

Alex anxiously awaits a crucial college recommendation from his English teacher and urges Steven and Elyse to butter Mr. Tedesco up on parents' nite at school - but the obnoxious Tedesco is so insulting that Elyse slugs him, and a horrified Alex entreats Steven to make amends. The usually calm and non-violent Elyse is amazed and ashamed at her uncharacteristic behavior, though Tedesco ""asked for it"". Steven visits him and after being subjected to disparaging remarks about his wife, winds up repeating her deed. Finally Tedesco, who does recognize Alex's intellect, accepts an invitation to the Keaton home where he alienates everyone again. Alex must decide whether a glowing recommendation from an influential but disgusting man is worth groveling for.

While Steven fights for his life in surgery, the family fights to remain optimistic about his condition. When Steven's surgery extends beyond the expected five hours, tension in the waiting room increases. A nervous Alex, however, begins to express acute concern only for himself fearing that he has inherited a weak heart, he searches in vain for his pulse. Lauren soon makes Alex realize that he is fixated on his own health to block the anguish he really feels for his father. While the Keatons wait, they receive hope and encouragement from Mrs. Hobart and Mr. Meyers, whose spouses are also undergoing surgery.

Alex discovers that his idol, young Uncle Ned, has a serious drinking problem when the bright, but ill-fated corporate whiz kid returns for a visit after losing another job.

Mallory's boyfriend, environmental artist Nick Moore, swaps his T-shirt, camouflage pants, combat boots and earrings for a three-piece suit and a haircut to impress Mallory's parents, but while Steven and Elyse love the new Nick, Mallory is ready to leave him.

While Andy is inspired by his parents' old love letters to try his hand at writing one to a kindergarten sweetheart, Lauren finds herself less and less able to spend time with Alex. She is struggling with her psychology thesis and is becoming increasingly depressed by her lack of significant progress. She confesses to the Keatons that she sometimes has the urge to quit, but Steven and Elyse encourage her to hang in there and keep working on it, much to Alex's chagrin. The day after she has broken yet another date with Alex to work on her thesis, Lauren complains to him that the project which once thrilled her has become incredibly boring. Having received a lukewarm response from her professor on what she has accomplished so far, Lauren finds the temptation to quit and spend more time with Alex too strong to resist. Alex happily assures her that she is making the right decision.

Steven battles the physical and psychological aftershocks of his heart surgery. As the hours drag on during Steven's quadruple bypass operation, the Keaton crew grows exhausted in the hospital waiting room. Awakened by Skippy's typically goofy entrance, they all snap to attention when Dr. Harrison appears. He assures them that the surgery has gone well, but Steven must still be observed closely for the next few hours.

Alex does some fancy footwork on the dance floor to impress Ellen when he thinks he is losing her because of their divergent interests. Alex feels he has to compete with Ellen's artsy friends for her attention and attempts to change himself to fit into her world.

Alex hires a tutor to help him with math, but his ""teacher"" turns out to be a 13-year-old genius who suddenly becomes more interested in Jennifer than in helping Alex. When Eugene, Alex's tutor, meets Jennifer he loses his concentration and Alex comes up with a scheme that will benefit both him and Eugene.

Alex sees Mallory and Nick leaving the Keaton residence in the predawn hours to elope, and unable to stop them, follows them to New Jersey where he finds the young couple taking a hard look at their decision. After Nick bumbles around the outside of the house with a 16-foot ladder, Alex makes a desperate attempt to keep his younger sister Mallory from marrying Nick. But they are too much in love to listen. It takes Erin and Mike, another couple, to give them perspective on their maturity.

The Keaton family unites in crisis when Steven suffers a serious heart attack. While Alex and Andy discuss the upcoming Presidential race, Mallory and Jennifer prepare for another legendary shopping expedition. Moments later, Elyse returns home from jogging, but Steven lags behind, explaining that his run was slowed by a burning pain in his side. Steven dismisses the pain, assuming it was due to something he ate, while Alex kids him that the pain was caused by the guilt of being a Democrat.

Elyse's younger brother and Alex's idol, Ned, makes a surprise visit. However, everyone is puzzled by the go-getter corporate executive's suspicious behavior.

With the FBI hot on Ned's heels for embezzling 4.5 million dollars in corporate funds, Elyse's ethical brother and Alex's idol tells the family why and where he hid the money.

When Alex's friend Greg dies in a car accident, Alex is thrown into a state of shock and begins to seriously question the meaning and purpose of his own life. Having been asked to accompany his friend on the fatal trip and refusing because it wasn't convenient, he is overcome by guilt. He tries to fathom why he was spared in the face of such selfishness, and begins to have encounters with Greg's ghost. His family urges him to get help.

While Jennifer steels herself for a showdown with school authorities, Steven and Elyse prepare to back her up in her fight against the school board's book banning policy. Even Mallory gets into the act and shocks the family by falling in love with the forbidden ""Huckleberry Finn"", which she ends up reading aloud to Nick. Nothing is solved at the meeting with the school principal, Dr. Hewitt, the head of the school board and Jennifer's English teacher Mr. Flaherty when the Keaton's refuse to comply with the new school ruling. Jennifer is crushed by the fact that Flaherty, whom she respects and admires, will not stand up to Hewitt and the board even though he claims to be completely on her side.

Cousin June returns to the Keaton household for a visit after a three year stay in London. All of the Keatons are eager to hear her tales of England, but they just can't seem to let her get a word in edgewise.

Seduced by an "older woman" of twenty-one, the hitherto inexperienced Alex is devastated to learn that she thinks of their relationship as casual.

Steven's assistant at the station is bright, talented, funny, witty...and in love with him. And it looks like Steven may be returning her affections. It becomes obvious that Steven's assistant, Stacey Hughes, is very much attracted to him. And after a rough evening at home, as brief fling begins to look better and better to him.

On his 18th birthday, Alex defies his mother and goes off with some of his buddies to celebrate at an out-of-town niteclub, and to his dismay, the irate Elyse shows up and confronts him.

Because of Elyse's pregnancy, the family decides to get a housekeeper, so Alex hires the lovely Karen Nicholson, a totally incompetent young lady whom the family immediately adores but Steven insists she must be fired. Despite the fact that Karen has no domestic skills and is rapidly destroying every appliance in the house, the kids love her and Steven has a difficult time trying to fire her.