The McCoys move from Smokey Corners, West Virginia., to a ranch in Fernando Valley, Calif., which Grampa McCoy has inherited from his brother Ben. They have also inherited Pepino, a ranch hand, and they meet their neighbors, Flora and George MacMichael. But Grampa finds himself homesick for ""West Virginny.""

The McCoys start a roadside eggstand and, inadvertently, an egg war with neighbor Harry Poulson.

The male McCoys try to outwit the female members by using money in the cookie jar to buy a shotgun rather than a dress for Kate to attend the PTA meeting. When the men concede defeat and they buy Kate a dress, things get even worse. Fortunately, the PTA president is able to correct their choice of dress.

The McCoys find themselves in trouble when they need $150 to meet a mortgage payment. Checking through all their wordly goods, they discover their only valuable asset is a rifle handed down to Grampa by his great-grandfather. Grampa finally decides parting with his treasure is better than borrowing money from his neighbor George.

Grampa McCoy takes over the supervision of Hassie and Little Luke when, after getting bad grades in school, Kate starts to discipline them. He soon learns it isn't as easy as he thought and is happy to turn the job back to Kate.

Grampa thinks he's made a sharp business deal when he sells some useless farm land, until he finds out the freeway is going through that part of their land. Luke and Kate feel Grampa has been swindled -- but Grampa's native honesty saves the day for the McCoys.

When Grampa thinks Luke is being henpecked by Kate, Luke decides to prove him wrong—and ends up sleeping on the couch in the living room.

Luke and Kate urge Grampa to invite Flora MacMichael as his date to attend the Valley Ranchers annual fall dance and box supper. Grampa will have none of it until he hears that Flora is the best cook in the county.

Grampa McCoy and his archrival George MacMichael enter a fishing contest. With the discovery that California fish are elusive if not intelligent, Grampa almost resorts to cheating.

The McCoys' neighbor Mrs Webster asks their support in her race for a seat on the City Council, but Grampa feels women have no place in politics. When he learns it is necessary to read and write in order to vote, he tries various subterfuges to pass the reading test. His innate honesty prevails, and he also assists the neighbor in her political ambitions.

Grampa's jealousy leads him to court and a confrontation with his romantic rival---the judge. Grampa finds a stranger beating his time with Flora and takes his revenge on Flora's apple tree. When Flora hauls him into court for refusing to pay damages, Grampa recognizes the judge as the ""stranger.""

Grampa and Luke invite their minister to the house for dinner to help Kate get on a church committee. Before the minister shows up, Grampa has given a billboard salesman permission to use the barn roof for an advertisement for a gambling house in Las Vegas. Luke solves the dilemma by painting out some of the letters in the advertisement.

Luke becomes jealous when a photographer for a national magazine comes to their ranch to use Kate as a model and is over-attentive to Kate from Luke's viewpoint. Grampa eggs him on, and they are both humiliated when they learn the photographer is a happily married man. He tells Luke how lucky he is to have Kate for his wife.

A hunting dog wanders onto the McCoy ranch, and when the owner, Joe Johnson, appears to claim him, Grampa tries to make a trade with him for the dog. Joe refuses until Grampa promises he will arrange a date for Joe with Flora MacMichael.

The McCoys are visited by Frank Goody and his attractive daughter from Smokey Corners, West Virginia. When Elvira starts playing up to Luke, Kate becomes jealous.

When Little Luke gets into a fight after classmates call him a ""hillbilly,"" the entire McCoy family becomes involved. Grampa finally sets things right when he is asked by the teacher to address the class, and he proceeds to tell them about the ""dumb hillbillies"" who helped build the country they are living in.

When Luke and Kate learn mailman Mr. Perkins is retiring at the insistence of his children, they decide Grampa should take things easy. Grampa feels he is not needed on the ranch, and he pretends to be ill. The family decides he is not yet ready for retirement.

After two years of marriage, Luke and Kate go on their honeymoon. Grampa: Walter Brennan. Kate: Kathleen Nolan.

Luke falls head over heels for a pretty swimming-pool saleswoman. Miss Eberle: Peggy Knudsen. Luke: Richard Crenna. Kate: Kathleen Nolan. Grampa: Walter Brennan.

Uncle Dave's tall tales impress all the McCoys except Grampa (Walter Brennan). Dave: Harry Shannon. Kate: Kathleen Nolan. Luke: Richard Crenna. Hassie: Lydia Reed.

The McCoys teach a wealthy couple the joys of simple living.

Luke and Kate join a young people's recreation group and suggest Grampa join the ""Young Old Timers."" He refuses, saying they are all old fuddy-duddies with no family interests. After consistently being left alone, he finally decides to investigate the old-timers group and is acclaimed by them as an artist at whittling.