Chip begins studying with a pretty co-ed whose disciplinarian father wants to know why her new friend is spending so much time with her. Meanwhile, on the eve of Steve and Barbara's first wedding anniversary, Dodie announces she is throwing a surprise party, but neglects to tell everyone when or where.

Uncle Charley and Barbara suspect that Chip and Polly are becoming serious about one another. Polly, unhappy at home because of her father's strictness, is afraid of losing Chip because of her parents' meddling. She asks Chip to elope, and taken aback, he asks his father for advice.

Barbara is flustered when she receives a phone call from a former college suitor, and is very apprehensive when Steve invites him to dinner. The entire family is anxious to meet her old flame, thus compounding her uneasiness.

Chip delights Polly with an expensive locket for her 18th Birthday and after their vague conversation, he thinks he's agreed to go steady, but Polly tells her mother that she has become engaged. Perturbed by her husband's probable reaction, Mrs. Williams arranges a luncheon to judge the seriousness of the matter.

Chip and Polly open a joint bank account and Chip takes on a box boy job at a supermarket to accumulate money for their future marriage. Later after she's had an argument with her father, Polly comes to the Douglases with her packed suitcase, but when Chip turns down the girl's offer to elope, she storms out.

Dressed as a cat for a costume party at the home of his employer in Bel Air, Steve goes for gasoline when his car stalls but the police arrest him as a burglar. Meanwhile, Polly notes that there is so much love in the Douglas household, that she just has to become a part of it.

Chip asks Steve's permission to elope, but before he grants it, he insists Chip give Mr. Williams the courtesy of asking his approval too. Chip goes to see Mr. Williams only to have him accusingly flaunt a private detective's report. Realizing that Polly's own father had hired a man to trail them, he storms out before asking for her hand.

Following their elopement to Las Vegas, newlyweds Chip and Polly are beset by nothing but trouble. The universal joint in their car gives out and they have to be towed into town. The hotel where Steve and Barbara stayed is no longer for honeymooners but for singles, and the newlyweds must spend their first night in separate rooms.

After Chip and Polly return from their honeymoon they spend a few days at the Douglases. Soon they move into their own college dormitory, and bridegroom Chip faces a father in law who refuses to speak to his newly married daughter.

Barbara becomes involved in presenting a fashion show for a woman's club luncheon, and Steve reluctantly agrees to become a model for a fashion show, but refuses at the last minute when he realizes he must wear a lacy, ruffled shirt and parade down a runway modelling it.

Chip becomes violently ill after eating Polly's cooking, and she learns from the family that Chip is allergic to some of the foods she's been preparing. Distressed, she feels it would be better for her husband if she left him.

Against his classmate's better judgement, Ernie uses the unwitting Douglas household as guinea pigs for an experiment assigned by his psychology teacher. He cuts inches off Uncle Charley's cane to make him think he is growing taller. Ernie soon finds his father Steve is a little less gullible.

Katie's mother gives Katie and Robbie a vacation by taking the triplets to St. Louis with her for a couple of weeks. Robbie figures that now is the perfect time to do all of the things they haven't been able to do when they had the boys to look after.

A boyhood friend from Bryant Park, rides his motorcycle back into Robbie's life and awakens Robbie's wunderlust with appealing tales of travel and adventure. Intrigued by Jim's stories of freedom, Rob agrees to take a holiday from Katie and the triplets.

Dodie and some of her girl classmates in the second grade get a big crush on Mr. Turley, their new teacher, and right away they make a batch of cookies for him. Dodie's crush begins to fade when she finds out that her Mr. Turley was once one of Barbara's students.

Level-headed Katie becomes a jealous, suspicious wife when a pile of circumstantial evidence stacks up against Robbie, as she suspects him of seeing another woman.

Ernie and his friend Elmore both flunk their driving licence tests, while their dates for a dance both pass. Ernie and Elmore take part in a ruse to conceal this situation from their dates, but instead they end up in trouble with the law when they realise they are stranded after a date.

Ernie is left in charge for one day when Steve and Barbara are off to Chicago for a golf tournament while Uncle Charley attends a string music festival. Little Dodie and her friend take a shopping excursion into town but don't have enough money for the bus ride home.

Dodie studying piano, Margaret on the violin and Susan at clarinet, comprise the 'Rondelay trio' and Dodie tells Steve and Barbara the good news that they'll practice at the Douglas house for their upcoming recital.

The rear bumper of Ernie's car is struck by a teenage girl in a parking lot. Ernie's car suffers no real damage but the other car's fender is crumpled. Before very long, this involves Ernie in an ill-fated romance.

Barbara leaves Ernie in charge of looking after Dodie after she has to go shopping. However Dodie goes to her friend Drucilla's house, and when Barbara returns he cannot remember where she is. After Dodie is found, Barbara sends them both to their rooms for the day. Then Ernie and Dodie rebel when they feel that they've been unjustly punished.

Uncle Charley is elated when he gets word that his pugislistic shipmate and buddy is going to visit him in a few days. However, Charley is forced to concede that times and people do change when the tough-talking, bad mannered ex-sailor he once knew isn't so terrible anymore.

Rob is laid off from work, but decides to move with Katie and the boys to San Francisco to accept a job at another company. They move into an apartment and meet several other tenants. One of them suggests Rob is always tired from the burden of supporting his family. Feeling disheartened by this and other remarks, Katie thinks that Rob doesn't want her and the triplets anymore.