Arnold and the gang must stop Big Bob from chopping down the oldest tree in town.

When the kids make their new teacher, Mr. Simmons, quit his job, the replacement makes them realize what they lost.

Helga drinks a potion to lose all feelings for Arnold.

Gerald's secret is revealed; he doesn't know how to ride a bike, so Arnold teaches him how.

Arnold and Gerald compete against Helga for the school newspaper.

When Harold is walking in the street, he finds a kitty that belongs to an old lady and he takes it, but then everybody appears, and Harold has to surrender the kitty to the old lady.

Schoolyard tradition has it that on the first Monday of June each year, the fifth graders throw the fourth graders into trash cans. So, Arnold and Gerald try to make a run for it. As more people are thrown into trash cans and the fifth graders know all the routes, Arnold and Gerald find out eluding the fifth graders is harder that they thought.

After Arnold accidentally kills Eugene's fish with a yo-yo, he must do something to make up for it.

An organ grinder's monkey kisses Helga, who's convinced she has caught 'monkeynucleosis'.

Arnold and Gerald do a spot of fishing, determined to catch the pond's biggest fish, the legendary "Big Caesar".

Gerald and Arnold get on the case when Timberly loses her Barney-esque doll.

The new girl is teased at school by Helga and the other girls, but she's soon accepted by everyone.

After Arnold saves Sid from an injury, Sid devotes himself to paying Arnold back with unending kindness.

Arnold and Gerald bunk off school, but their day is ruined by their fear of being found out.

Arnold and Gerald go around the city following "Porkpie", a mysterious man caught on film. They suspect, because of the clues, that Porkpie are planning to kill "Marty", who turns out to be Mr. Green.

In this variation of "The Tell-Tale Heart", Phoebe plagiarizes from a poetry book and uses one of the poems as her entry in a poetry contest. She wins, with her prize being a trophy resembling poet Emily Dickinson. Then, the trophy haunts Phoebe into confessing.

Wolfgang and his gang of fifth graders challenge Arnold and his friends to a football game, but he has to first persuade them that his plays are good enough for them to win.

Gerald, getting tired of his family bugging him, moves out of his home and into Arnold's boarding house, only to realize emancipation is not all it is cracked up to be.

Gerald becomes an entrepreneur out of selling watches until the market becomes saturated.

Rhonda and Nadine fall out over working on a project at school, leaving Arnold to work with both of them separately.

Arnold and Gerald send the neighborhood alien crazy as they broadcast a mock Halloween radio show.

Arnold's Grandpa enters a Chinese Checkers tournament to reclaim his pride lost forty years ago. Robby Fisher's name is a parody of Bobby Fischer.

Helga's mother tries to let her and her father, Bob, bond.

Arnold follows in his Grandpa's footsteps and competes in the annual block party eating contest. After much munching Old Football Head goes stomach to stomach with eating legend Seymour 'The Disposal'.

Rhonda gets glasses and finds out what it is like to be a "Geek".

Helga uses Stinky as her boyfriend to try to make Arnold jealous.

Arnold develops a crush on Miss Felter, a substitute teacher, thinking he is having dinner at her house, only to realize that the one she invited was her fiance, whose name is also Arnold.

Phoebe becomes hall monitor and asks Helga for tips. She becomes overwhelmed by the "power" and soon everyone wants the old Phoebe back, even Helga once she realizes Phoebe's also giving her detentions.

Harold runs away from his Bar Mitzvah, thinking he will retain his childhood this way.

Arnold and his friends get Coach Wittenberg to be their new bowling coach.

The ghost of a former boarding house resident is believed to have been causing strange occurrences in there when Arnold and Gerald find an old pair of glasses believing to have belonged to him.

After finding out that his idol is a haughty, primped actor, Eugene sets out to become bad.

Helga and Arnold fall asleep and have their own "parody/dream" of the opera Carmen.

Arnold and a descendant of his grandpa's arch enemy, Rex Smythe-Higgins, compete in a boat race.

Teachers of Arnold's school go on strike because of inadequate funding; He and his friends are on cloud nine, only to find out that every lost school day will be taken from their summer vacation.

After creating an idea for a parade float, Arnold is confident of it showing up in a parade.

A lounge singer moves into the Sunset Arms after renouncing his songwriter, who also moves there.

While feeling the effects of laughing gas, Helga leaves a confessional message of love on Arnold's phone machine. She then has to get into the boarding house in order to erase the message.

As punishment for shoplifting a ham, Harold is forced to work for Mr. Green at his butcher shop for a week. Later, after his work shift to pay for it is over, he soon learns that he actually likes his new after-school job and doesn't want to stop working there, much to the dismay of Mr. Green.

Arnold becomes a hot (and dangerous) hitter. He keeps injuring people everytime he swings the bat. Afraid of hurting more people, Arnold refuses to play ball. Mickey Kaline helps him out.

Mr. Hyunh has a talent for country singing, so Arnold and Gerald, after recording a CD with him at the local studio, become his managers and make him a big star, much to his dislike.

Grandpa becomes tired of dealing with the boarding house and decides to sell. Arnold has to convince him how important it is for everyone to remain in the boarding house and what they would lose if it was sold.

Gerald's voice is deepened after having his tonsils out, just a few days before the school recital.

Sid pretends that Arnold's room is his, since he's ashamed of showing his real room to Lorenzo.

Patty challenges Helga to a fight after Helga gets on her last nerves by picking on her once too many.

Stinky's simple life changes after he becomes the surprise new spokesman for Ya-Hoo Soda.

Olga gets engaged to a con man who does not exactly woo Helga as he did the rest of her family, but she decides to let the marriage happen so Olga can be miserable. But she is given a change of heart from Arnold, and attempts to stop it.

Curly gets enraged after a minor playground mix up. He locks himself in the principal's office and refuses to come out.

Phoebe wins a chance to meet her favorite singer, only to find out that he doesn't write or sing his own songs.

Grandpa thinks he's going to die soon because no one in his family ever made it past his age. He prepares to die, and Arnold tries to convince him that life is still worth living.

When Bob has to go to a business meeting, Miriam and Helga are forced to go on the family road trip by themselves.

Principal Wartz gives Sid a detention believeing he placed fake vomit so he could trip over, even though it wasn't Sid who put it there. As a result, Sid seeks revenge and reates ""Revenge Doll"" of Wartz's face, like they do in tribes. He thinks he killed Wartz with the curse. Arnold thinks he's paranoid, even though there are a few clues hinting out that Wartz is dead.

A roller coaster breaks down while Eugene and Arnold are at the top of its tallest drop.

After the results of an aptitude test are announced, Harold gains self-confidence and Helga feels dumber.

Oskar gets a job as a newspaper carrier but uses Arnold as cover for his laziness.

Arnold finds out Iggy wears bunny pajamas with feet in them, and Arnold accidentially spills the beans to Sid and Stinky, ruining Iggy's cool image.

Bob hires a nanny to help Miriam around the house, much to Helga's dismay. From this moment on, Helga attempts to scare the nanny away.

A. All the kids are paired with adults with interesting jobs except Arnold, who is forced to spend time with the Jolly Olly, the Ice Cream Man.

Harold is invited to Rhonda's party and befriends the female bully, Big Patty.

The Coach wants to remarry Tish and asks Arnold to be his best man. Along the way, Arnold teaches the coach a thing or two about love and sacrifice.

Rhonda holds a cool-people-only party at her house. In retaliation, Arnold and his friends hold a "geek" party on the roof of his boarding house further up the street, leaving Rhonda's party deserted.

Helga, lost in a love reverie, writes 'Arnold loves Helga' on a wall, but changes the name to 'Lila' when the kids approach. Lila thinks that Arnold loves her until he explains the mistake. Then he falls for Lila and she is forced to break up with him.

The kids compete in a grand prix race against each other.

Arnold and Helga both think they are having the worst Thanksgivings ever. Arnold's Family are celebrating President's Day, and Olga is at the Pataki house. When Arnold and Helga go to Mr. Simmons' house, they discover he has a obnoxious family, so they think their families aren't so bad after all.

Helga tells jokes about her classmates, who take offense to it.

The town is flooded and Arnold's class is trapped in the school.

P.S. 118 is holding a Spelling Bee, and Helga wants to win one trophy to get out of Olga's shadow, but Pheobe has to back out of the competition for Helga to make it.

Arnold, Grandpa, and friends reenact the Pig War.

Arnold is okay with working with Gerald at Mrs. Vitello's flower shop after she's injured and puts Gerald in charge, but not with working for Gerald, which causes the friendship to hit a snag and Arnold quits.

As a science assignment, Arnold and Helga have to work together, and get along with each other, for 24 hours in the Sunset Arms greenhouse.

Arnold has to do a book report, and he decides to do it on his favorite author, Agitha Cawfield, but he sees her bad side when she is very crabby & rude to him.

Lorenzo, a neurotic rich kid, comes to P.S. 118. All the kids try to help him become an average kid.

Arnold snaps at school after Helga tries his patience once too often.

Arnold is in charge of the school dance. He books has-been singer Dino Spumoni, and when he sings a depressing "good-bye" song, all fingers point at Arnold.

The school is doing the play "Romeo and Juliet". Arnold lands the role as Romeo so Helga will do anything to beat out other girls to get the part of Juliet, so that she can kiss Arnold in the final scene.