David (Tobey Maguire) and Jennifer (Reese Witherspoon) Wagner are twins, but  they lead dramatically different high school social lives. He’s a shy, lonely and not happy with his life in this world, who flees reality by watching Pleasantville - a 1950's b&w soap opera, where everything is just...pleasant, and he’s an expert on every episode. She’s concerned mainly with her appearance, relationships and popularity, and sexually far more active than her brother. This Saturday is important for both of them. Mrs. Wagner (Jane Kaczmarek) leaves Jennifer and David alone at home while she heads on vacation with her boyfriend. David is preparing for a Pleasantville 24-hours marathone, with a trivia questions at the end, and the chance to win $1.000. Jennifer is preparing for a date with the coolest guy of the school Mark Davis, to watch an MTV concert toghether.  The twins begin to fight over the use of the downstairs TV, but the remote control breaks and the TV cannot be turned on manually. A mysterious TV repairman (Don Knotts) shows up uninvited, and quizzes David on Pleasantville before giving him a strange-looking remote control. David and Jennifer resume fighting... and they suddenly find themselves in Pleasantville, transported into the television, ending up in the Parkers' living room as Bud and Mary-Sue Parker. David tries to reason with the repairman (who communicates with him through the Parkers' TV set) but succeeds only in chasing him away. David and Jennifer must now pretend they are, Bud and Mary Sue, at least for 2 weeks, when the repair man will come back.

It’s breakfast time, served by stay-at-home mother Betty Parker (Joan Allen), and consists of generous servings of  many fatty foods. Jennifer, a '90s girl, is disgusted at the thought of eating so much. On the way to school, David tries to make Jennifer understand that they should integrate themselves into this "backwards" society to get out of  this situation, but she didn’t like the idea. The pair watch as a group of firemen rescue a cat out of a tree, and the meeting with Skip Martin (Paul Walker), the captain of the basketball team, change her mind. In order to keep the plot in line, Jennifer agrees to go on a date with Skip, although the two have very different ideas of what a date constitutes. The date between Skip and Jennifer turns out to be the first catalyst for change in the town, Skip having no knowledge of sex until Jennifer introduces him to it. The plot is further thrown out of sequence when Bud’s boss Mr. Johnson (Jeff Daniels), who runs the soda fountain, becomes dissatisfied with his boring, mundane life. Bud initially attempts to convince him to carry on, saying that even if Mr. Johnson does not like his job, he should still do it anyway, but David soon realizes his error and gives Mr. Johnson an art book, encouraging his true passion.

Meanwhile, Skip tells the other boys about sex, and soon the teenagers begin to experiment, leading to a sort of sexual revolution. Betty is curious (leading to a reversal of the sex talk between her and Mary Sue/Jennifer) and, knowing that her husband George (William H. Macy) would never do any of the things Jennifer describes, engages in masturbation. This causes a nearby tree to spontaneously combust. David, realizing the firemen have no other duties other than to fetch cats out of trees, teaches them how to put out fires and is awarded a medal. He also gets attention from a beautiful cheerleader named Margaret (Marley Shelton), who bakes him oatmeal cookies, the same cookies she was supposed to bake for a boy named Whitey (David Tom). David’s act of heroism has inadvertently changed the storyline, but he seizes the moment and asks Margaret out for a date. When the TV repairman returns and confronts him, David turns off the TV, relinquishing his ability to go home in the process.

People in Pleasantville begin to explore hidden abilities and revel in their new freedoms. Mr. Johnson begins to paint, while Betty finds that housework no longer interests her. The basketball team loses their first game, students begin visiting the public library and reading books recommended by Jennifer and David. Ironically, Jennifer, who has never shown any interest in school, finds she likes reading so much that she rejects Skip in favor of a book by D. H. Lawrence and gains color.

Pleasantville is changing. There’s even a rainy day. Slowly, certain objects begin turning multicolor... flowers, dresses, and the faces of people who have experienced bursts of passion or change. The only people who remain unchanged are the town fathers, led by Mayor Big Bob (J.T. Walsh) who sees the changes as eating away at the moral values of Pleasantville. A town meeting is called. Betty leaves George and the kids - she is in love with Mr. Johnson and cannot hide her 'colored' face anymore. Rioting begins in Pleasantville, touched off by a nude painting of Betty on the window of Mr. Johnson’s soda fountain. The soda fountain is destroyed, piles of books are burned, and anyone who is “colored” is harassed in the streets. David earns his color by defending Betty from a gang of toughs led by Whitey.

He transforms from a wimpy loser to a strong leader who advocates resistance to the new “Pleasantville Code of Conduct”, a list of rules preventing people from visiting the library, playing loud music, or using paint colors other than black, white or gray. In protest against the mundane Pleasantville outlook, david and Mr. Johnson paint a colorful mural. For this they are thrown in jail. They are subsequently brought to trial in front of the entire town. Mr. Johnson is repentant but David speaks out, finally arousing enough anger and indignation in Big Bob to turn him colored as well.

George earns his color when, in the courtroom, he cries for the loss of his wife. With this, the entire town becomes emotional, therefore colored, and the people of Pleasantville are finally introduced to the rest of the world.

The scene of J.T. Walsh in front of the bowling alley scorecard recalls Patton's speech in front of the American flag in Patton (1970) 

The courtroom segregated into black-and-white characters downstairs and "colored" characters upstairs recalls To Kill a Mockingbird (1962)

The scene in which Tobey Maguire raising his arms in the rain recalls The Shawshank Redemption (1994). Gary Ross thought it was an original idea, and didn't realize the connection until after the film was released.

The Native American in the test pattern behind Don Knotts changes to angry and then sad as the movie progresses.

During the publicity campaign surrounding the film's release, there was a contest for a trip to Pleasantville, Iowa (the smallest Pleasantville in the United States).

The two books that Bud (David) narrates to the teenagers of Pleasantville, "The Adventures of Huckleberry Finn" and "Catcher in the Ry," are the two most widely banned books in the United States.

In the original screenplay, the TV Repairman was to be played by Dick Van Dyke and the name of the repair company was Rob's TV Repair (Rob was Van Dyke's name on his first show) In a subsequent draft, the name in the script was simply TV Repairman, leaving room for Don Knotts.

When Jennifer enters Pleasantville, she becomes a character named Mary-Sue. "Mary-Sue" is a term that originated in fan fiction to describe a character who comes into the character's lives and completely solves all of their problems. It is also a fan-fiction term for when the author (usually female) inserts herself (as a character) into the story.

Since every scene from the middle of the movie on had to be in some way digitally changed to have black and white characters interact with characters who are in color, technically this film had the most digital effects shots until Star Wars: Episode I - The Phantom Menace (1999).

The jukebox in Mr. Johnson's malt shop is a 1952 Seeburg M100C, known in collector circles as the "Happy Days" jukebox due to its appearance in the opening/closing segments of the ABC-TV series.

The scores projected during the bowling alley scene indicate all the bowlers are on pace for final scores of 230 or better. Two bowlers have perfect scores through eight frames.

The sign at the end of the movie points the way to Springfield. Springfield was the setting of '50s TV show "Father Knows Best" (1954) which "Pleasantville" (the fictional TV show) was at least partially based on.

For the sequence where Bud is applying the gray makeup to his mother, the color of the makeup was actually green. When they had to "black-and-white" the scene, the shades of green came out the best for the appropriate shades of her "gray" make-up. Conversely, when Betty first visits the soda shop, she is in full gray makeup which meant that Joan Allen was shot wearing full green make-up that is subsequently removed by Bill Johnson (Jeff Daniels).

J.T. Walsh's final film role.

Don Knotts was not available to return for looping. The film's narrator, comic and impersonator Craig Shoemaker, was hired (uncredited) by the editor to fill in and do the voice work for Don Knotts.

The back lot street set where Bud and Mary Sue's house stands is located at Warner Brothers "Ranch" studio complex in Burbank, California. The main house was a new facade built for the movie but directly across the street, clearly seen in a number of scenes, are houses once occupied by other famous T.V. characters like Gidget, Hazel and Samantha Stevens. Margaret"s house (where Whitey drives up in his car at night) was used as the residence of Mrs. Kravitz in "Bewitched" (1964) and "The Partridge Family" (1970).

In a number of scenes, you can see the house used in Lethal Weapon (1987) just across the street from Bud and Mary-Sue's.

Bud brings Mr. Johnson an art book from the library titled "The World Of Art" by an author named Edward Bissell. The book is purely fictional being made just as a prop for this film