Welcome Back, Kotter Season 4

While Horshack adjusts the married life, Epstein sets up an interview for a job. Washington gets the job before Epstein, unaware that it's the same job. The two get into a fight and end up in a gym ready to box.

Beau plays a number or pranks on Mr. Woodman.

Arnold gets upset when the other Sweathogs tease him about not being able to provide for Mary, and he vanishes. Mary finds him and convinces him not to worry, and the two get married.

Arnold's relationship with Mary gets serious. Then he finds out he has to move and leave the school. Upset, Arnold decides to propose marriage to Mary. She accepts.

Freddie and Juan plan to do an act together for the upcoming talent contest, while Carvelli has some bribed judges up his sleeves. Arnold and Beau take over as judges, leaving Murray in the third spot.

Convinced that the school newspaper is too dull, Juan sets out to turn it into a tabloid, bringing down his friends' names in the process.

To get up his nerve with Mary, Carvelli offers Arnold liquor. He doesn't like the idea at first, but as time goes on, he becomes addicted to drinking; developing a scary and unlikable new personality that only turns Mary away.

Mr. Woodman's niece Kelly is babysitting for the Kotters when Juan drops by the apartment. The two abruptly fall in love and decide to move in together, but the romance begins to crumble when it seems that they can't respect one another's interests.

Vinnie is forced to deliver a baby in an elevator.

Juan asks Vinnie to marry his immigrant cousin.

Vinnie is saddened when his new coat is stolen.

The Sweathogs opt to change Mr. Woodman's tired old school song.

After Horshack refuses to disect a frog in class, his grade is in jeopardy.

A younger student begins to imitate Freddie, not much to Freddie's liking.

Vinnie becomes depressed when it seems that he has lost his way with women.

The gang is liable to get in trouble when the x-rated film Carvelli brought into school is accidentally mixed up with a film on sexual education.

When Mr. Woodman comes to Vinnie's hospital for an operation, Vinnie loses him and he and the other Sweathogs try to find him.

The Sweathogs remember how they tried to buy a used car from Vinnie's uncle.

Horshack saves a lonely, overlooked girl named Mary Johnson from commiting suicide by jumping off the ledge of the school.

Vinnie throws the Sweathogs out of his new apartment.

With Barbarino now an ordlery at a hospital, the Sweathogs try to get jobs there, too. Meanwhile, Kotter tries to get the gang to return to school.

Gabe announces that he is now the vice-principal and Mr. Woodman is the principal. The Sweathogs are pleased, until Gabe gets strict. After Vinnie visits the school to tell the gang he's dropped out, the other Sweathogs decide to follow in his footsteps.