Act One

Two New Jersey teens, Josh Baskin and Billy Kopecki, practice an MTV-style, hip-hop dance routine as the curtain rises ("Come on, Baby"). A group of teenage girls, including fourteen-year-old Cynthia Benson, enter. Josh, who has a massive crush on her, tries to calm down, act naturally and just talk to her ("Talk to Her"). Cynthia approaches Josh, and he freezes. After she leaves, Billy tries to convince Josh that Cynthia likes him and gives Josh advice on how to talk to her. We see Cynthia and the other girls arranging their hair and adjusting their makeup as they complain about the time it takes to grow up.

As Josh continues to wonder how other boys can talk to girls with apparent ease, his parents enter. They announce that the family will attend the local carnival. When Josh mentions that he'd rather stay home and play his new computer game, his parents wonder if Josh's sour mood is due to a new adolescent interest in girls. Billy reenters and tells Josh that Cynthia will probably be at the carnival, alone. Again, Billy coaches Josh on what he should say to her. As the two boys sing and dance their hip-hop routine, the carnival appears around them. Josh convinces his parents to give him and Billy money for the Wild Thunder rollercoaster ride. Billy notices Cynthia has joined the line behind them. Once more, Billy urges Josh to talk to her. Just as Josh gets up his courage to speak, sixteen-year-old Derek enters and places his arm around Cynthia, who mentions with awe to Josh and Billy that Derek drives. When Josh and Billy get to the front of the line, the ticket taker tells Josh that he is not big enough to ride the Wild Thunder.

After Cynthia and Derek pass them to get on the ride, Josh walks off and finds himself in a deserted part of the carnival. He works off his frustration by again doing his hip-hop routine as a row of funhouse mirrors appear behind him. As Josh looks at himself in the mirrors, he notices an antique arcade machine: a glass box encasing a red devil's head with the words "Zoltar Speaks" written across the top. Josh follows the instructions to insert a coin into a ramp leading to Zoltar's mouth. When nothing happens, Josh kicks the machine and it comes to life. Music plays, lights flash and Zoltar begins to move. It instructs Josh to make a wish. Josh wishes to be big and hits the machine again, causing the coin to drop into Zoltar's mouth. As thunder sounds and lightning flashes, Josh notices that the power cord to the machine is not plugged in. He runs home and dives under his covers.

The following morning, from the kitchen of the Baskin house, Mrs. Baskin tries to wake Josh, yelling up to his room. As she tidies up the kitchen and sets Josh's breakfast on the table, she considers her life as an overworked wife and mother ("Say Good Morning to Mom"). Upstairs, a now fully grown Josh gets out of bed, looks in the mirror to inspect a pimple on his face and discovers, to his horror, that he has become an adult overnight. He dives into the closet just as his mother enters to collect his dirty laundry. He disguises his now deeper voice and somehow manages to avoid being seen by her. When his mother leaves the room, Josh tries unsuccessfully to fit into a pair of his twelve-year-old self's jeans, finally grabbing one of his father's sweatsuits. As Josh tiptoes across the kitchen towards the door, the baby begins to cry. When Josh tries to quiet her, she screams even louder. Hiding under the kitchen table, Josh again just barely manages to avoid being seen by his mother; however, his mother lifts the tablecloth, sees the adult Josh and, assuming that he is a burglar and kidnapper, offers him her purse. Josh tries to tell her who he is, but, when she grabs a handheld mixer and begins yelling for the police, he runs out of the house.

Josh is a bit hysterical, wondering how he has gotten so big so suddenly; soon, he remembers Zoltar ("Big"). After wishing that he could undo what has happened, Josh goes to his junior high school to find Billy. Billy, like Mrs. Baskin, doesn't believe this grown man could be Josh, but Josh finally convinces Billy by telling him things that only Josh could know and by performing their hip-hop routine.

Billy and Josh are in the Port Authority Bus Terminal in New York City, surrounded by an assortment of commuters, panhandlers and various other people who live and work there. After being approached by a panhandler, Billy and Josh decide to ask someone at a video arcade where they might find a Zoltar machine. The arcade manager suggests that they ask the Bureau of Arcades and Amusements for a complete list of carnivals. He gives them the address, telling them to expect a three-to-four-week wait. When Josh complains that he can't wait that long, Billy points out that most kids would love the chance to be grown-up and do whatever they want, without fear of parental reprimands ("Big Boys"). After Billy assures Josh that getting a job will be easy, Josh eventually agrees that this is his chance to feel grown-up feelings without waiting to grow. After suggesting that Josh find a place to sleep in the terminal, Billy leaves to go back home. Josh, alone and scared, calls his mother, but she still believes that the grown-up Josh has kidnapped her son. A police detective grabs the phone from her, and Josh quickly hangs up. He sits down and begins to cry.

The next day, Josh has found himself a large Manhattan toy store, where an animated clock is whistling, accompanied by a chorus of salespeople, wooden soldiers and clowns inviting customers to come in. Josh, attempting to sound and look like an adult, tells a salesperson that he wants a job and is directed up to the personnel office. He is then accosted by a little boy who fires a ping pong ball at him from a toy space gun. Josh chases the boy as the employees and the animated clock continue inviting customers into the store. George MacMillan enters, approaches a little girl and asks her if she would rather play with her doll or with an evil-looking space action figure that he holds in his hand. The girl's mother intercedes, dragging the girl away from MacMillan. He then approaches a little boy with the action figure; the boy screams and runs away. Josh, now holding a toy space gun and chasing the boy who shot him, crashes into MacMillan and knocks him down. When MacMillan asks Josh if he is trying out the toy gun for his son, Josh responds that he merely wanted to see if the gun was any fun. MacMillan, owner of the MacMillan Toy Company, introduces himself to Josh and tells him that his company is having trouble coming up with a Christmas toy that will sell. MacMillan bemoans the difficulty of understanding what kids find "fun." Josh points out why several of MacMillan Toy Company's formerly big-selling games and toys aren't fun anymore. The store employees push out a large toy keyboard, upon which Josh and MacMillan then dance, first plunking out "Chopsticks" and then "Heart and Soul." After they dance, MacMillan offers Josh a job at his company ("The Time of Your Life").

Billy accompanies Josh on his first day at MacMillan Toys, a very sleek and cold corporate office. As Josh and Billy speak to a chilly receptionist, a chorus of junior executives welcomes them to MacMillan Toys, describing what they do and how the company was founded ("Welcome to MacMillan Toys"). Miss Watson, an executive secretary, arrives to take Josh to his new office as the junior executives continue to sing their welcome. Susan Lawrence, Vice President in charge of Marketing, enters with an armful of folders; she is followed by Paul Seymour, Vice President of Product Development, who is carrying a "Dr. Deathstar" action figure, the latest hope for MacMillan's Christmas catalogue. Susan complains that she can't get any work done because of her secretary's impending wedding ("My Secretary's in Love"). Josh, rushing to find the conference room where he is to meet MacMillan and the other executives, bumps into Susan and knocks her folders on the floor. Rick Birnbaum, Ron Barrett and Arthur Lipton, the Vice Presidents in charge of Advertising, Production and Promotion, respectively, arrive as Josh helps Susan pick up the folders. Susan and Paul introduce themselves to Josh. As they all wait for the conference where Mr. MacMillan will announce the season's top toy design, Paul boasts that the conference will go smoothly and quickly. When Mr. MacMillan arrives, he and Josh announce that the Dr. Deathstar figure is not fun to play with; MacMillan then announces that he is halting the planned release of the toy. He demands that the executives reevaluate their previous toy designs and introduces Josh to everyone as the new Vice President in charge of Product Evaluation. As MacMillan shows Josh his huge, toy-filled office, Paul complains about MacMillan's decision to drop the toy, based solely on Josh's opinion. Billy meets Josh in his office and is shocked at its large size. Josh discovers that Miss Watson will get them all of the junk food and videos that they request; he even asks her to type Billy's algebra homework. After Josh explains to Billy that his job is to play with all of the new toy prototypes and discover which ones are fun, they start to realize that being big can be fun ("Big Boys – Reprise").

Elsewhere, Susan has broken up with Paul and immediately gets a headache ("Office Politics"). Susan goes to Josh's office to ask if he has any aspirin but interrupts a game of Astro-Blaster between him and Billy. Billy introduces himself to Susan as Josh's Special Assistant for Research and Testing. Josh mentions that Susan should see the apartment that he has been given, which he is free to furnish any way he wants. Susan takes this as an invitation and accepts. She leaves Josh's office, excited and flushed; she has accepted his invitation as Paul and the junior executives watch on with jealousy.

Billy and Josh enter, looking slightly green and carrying shoulderbags and backpacks filled with junk food. After discussing how many hot dogs they've eaten over the course of the day, they pretend to vomit and squirt strings of Silly String all over each other. Josh's large loft appears around them; it is filled with the kinds of things a thirteen-year-old boy might wish for: arcade games, a huge TV, a Coke machine, pinball machines, a basketball hoop. Josh mentions that he has two tickets to Saturday's Knicks vs. Bulls game; he tells Billy that he'll meet him at the game after attending a company party. Susan then appears, carrying a bag of groceries. Billy soon leaves, and Susan, who is nervous and excited to be alone with Josh in his apartment, gives him the bag of groceries, which contains caviar and champagne. Josh gets two glasses — plastic mugs with NFL logos on them — as Susan nervously talks about her decision to come over. Josh asks about the caviar; Susan mentions that it is Beluga and then spreads some on a cracker. He tastes it and immediately spits it out; Susan gives him the champagne to drink, which he also spits out. Josh pulls his shirt out of his pants, wipes his tongue on it, finds a can of Coke and gargles with it. As Susan continues talking, Josh asks her what games she wants to play. He mentions a number of games that he has in his apartment, finally realizing that all of his toys are for boys ("Do You Want to Play Games?"). Josh then mentions that he can give Susan stars and presses a button on a remote control unit; the lights go out and the walls and ceiling are covered with pinpoints of light ("Stars, Stars, Stars"). Josh tells her that he found the little planetarium at the Museum of Natural History and points out constellations; Susan joins Josh in looking at the stars. Susan, realizing that she is sitting on Josh's bed, admits that she was hoping Josh would ask her to spend the night. Josh immediately invites her to spend the night for a sleepover party; he gives her a pair of pajamas and hops up to the top bunk of his bunk bed. He then leans over the top, dangling his fists, and tells her to pick a hand. When she does, he gives her the "Official Startraveller's Compass" that he was hiding in his hand. Although a bit confused and even disappointed, Susan thanks him, mentions how wonderful the evening has been and goes to sleep.

Now it is Saturday. At the chic, black-tie company party in progress in the garden of a Midtown Manhattan restaurant, MacMillan employees are dancing stiffly as an offstage band plays. Paul shows Lipton a copy of Josh's job application, which is filled with the kind of answers that a twelve-year-old would write. As Paul tries to show Susan the application, Josh enters in a white dress suit; everyone applauds his entrance. Josh then gives Susan her lipstick, which he mentions having found behind his bed. Paul becomes very upset. After Mr. MacMillan greets Josh, Paul demands that Josh play a game of Toss Your Cookies. When Paul misses on his cookie throw, he blames Josh, claiming that he hit his arm. Josh denies this and refuses to give him back his cookie; Paul jumps on Josh and starts beating him up. Susan pulls Paul off Josh, accusing Paul of being jealous and demanding he return to her his set of keys to her apartment. Susan goes to comfort Josh as Mr. MacMillan takes the floor and demands that the executives find a way to connect with kids. Josh suggests that everyone should dance and he and the kids who have come with their parents begin to do so ("Cross the Line"). MacMillan threatens to fire anyone who doesn't dance — including Paul, who has been trying to show Mr. MacMillan Josh's personnel file. MacMillan tells everyone that they have three days to come up with the design for a new Christmas toy. Susan kisses Josh, and the dance goes into slow motion. When Billy enters and tells Josh that the Knicks/Bulls game starts in fifteen minutes, Josh tells him that he can't go with him. Josh leaves with Susan as the dance continues; Billy stares at them as the curtain falls.

Act Two

Back in their New Jersey neighborhood, Billy is throwing away all of the things that he has shared with Josh: the baseball bat with which Josh taught Billy how to bunt, their fourth-grade Field Day medal, Josh's dirtbike pedal, their two-way walkie-talkie system and the list of carnivals that he has received from the Bureau of Arcades and Amusements. Mrs. Baskin enters, carrying a box from the bakery. She mentions to Billy that today is Josh's thirteenth birthday and that she bought a cake, just in case he came home. Billy assures her that Josh will return soon and exits, retrieving the list of carnivals from the trash. Now alone, Mrs. Baskin reflects on life and fondly remembers Josh's childhood, wishing that she could have stopped time to keep him from growing up too quickly ("Stop, Time"). Suddenly, Josh enters and stares at his mother as all of the neighborhood kids surround Josh, clapping their hands and wishing him a happy birthday. Cynthia picks up the cake that Mrs. Baskin has left behind, and the candles burst into flame as we hear Zoltar's voice. Josh screams and collapses. All goes dark ("The Nightmare").

It is 4:00 a.m. Susan, who is still working at her office desk, notices Josh asleep on the floor in front of her sofa. She is working on a game that involves boxing with oversized boxing gloves while standing in a Hula Hoop and wakes Josh to ask for help. She and Josh, each standing in their hoops, begin to box. They continue playing until they eventually tumble out of their hoops, rolling around and hitting each other. Suddenly, Josh finds himself on top of Susan. He quickly rolls off, and they remove their gloves. Susan suggests they try to imagine that they are kids and asks Josh to pick an age; he suggests thirteen. When he asks Susan what she liked to do as a thirteen-year-old girl, she has trouble remembering but soon recalls how she was constantly busy with dance classes ("Dancing All the Time"). She convinces Josh to ballroom dance with her, and Young Josh appears. As Josh and Susan dance, Young Josh wonders about what men and women do together. Older Josh wonders how a woman kisses a man ("I Want to Know"). They continue to dance until, finally, Susan and Josh embrace.

It is the following morning. We see the exhausted and disheveled MacMillan executives greeting each other. Soon after Miss Watson arrives, the elevator doors open and Josh enters. He is dressed in an Armani suit, wearing dark glasses and, unlike the others, full of energy. He greets Miss Watson exuberantly and asks her to make some coffee for him ("Coffee, Black"). Josh tells her that he has come up with a great idea for the Christmas toy and asks her to contact the various company departments. With Miss Watson following closely behind, Josh finds the other junior executives, shows them his design and tells them what he needs from their departments. As Josh moves through the company, Paul shows Mr. MacMillan his own design: a bar for kids, stocked with tiny liquor bottles. MacMillan tells him that the idea is ridiculous and goes back to his office, where Josh and the other excited executives meet him. They tell him that Josh has found the perfect toy, but, when MacMillan asks to see it, Josh tells him that he'll have to wait for the presentation meeting on the following morning. After a tense moment, MacMillan throws his arm around Josh, praising him to the other executives. MacMillan demands that the others make sure that Josh gets whatever he needs. Later that day, Billy arrives and shows Josh the list of carnivals that has finally arrived. Josh informs him that he doesn't want to go back to being a kid anymore. He even offers Billy a job if he decides to find the Zoltar machine and make the same wish. Billy becomes very angry, and Josh accuses him of being jealous. Susan, who does not see Billy, enters and kisses Josh. Billy storms out as he wishes Josh a happy birthday. Susan, not realizing that it is Josh's birthday, invites him to accompany her to dinner with her friends. Josh is excited at the prospect of attending a grown-up dinner and eagerly accepts.

Nick and Abigail, along with Tom and Diane, two married couples who are friends of Susan, sip drinks and eat caviar and crackers in a stereotypical "yuppie" living room while listening to classical music. They all discuss Susan's love life and anticipate meeting the new, wonderful boyfriend about whom she has told all of them. Susan and Josh arrive. Susan's friends greet Josh, scrutinizing him the way that close friends do, and warn him not to hurt her. Josh, who doesn't smoke or drink, immediately impresses the friends with his unpretentiousness. The women all go into the kitchen, and Abigail and Diane tell Susan how wonderful and adorable they find Josh ("The Real Thing"). Meanwhile, Josh and the other guys talk in the living room; Tom offers Josh the tray of caviar. After making sure that the caviar isn't Beluga, he tries some. He immediately spits it out, finds a throw pillow on the couch and wipes his tongue on it, leaving a big black smear. The women return from the kitchen with a tray of steamed artichokes and a bottle of champagne. Abigail sees the pillow, forces a laugh, turns it over and throws it back on the couch. She then asks Josh to open the bottle of champagne for a toast, but he has no idea how to do it. The others begin eating the artichokes and Abigail, seeing the trouble that Josh is having, asks Tom to open the bottle. Josh, who has never eaten an artichoke before, takes a big bite off the top. He winces as he tries to chew it. Nick then asks Josh to move Tom's brand new BMW before he gets a parking ticket. Josh, who has never driven, hesitantly takes the keys. As they patiently sit and wait, an enormous crash is heard. Tom quickly exits. Josh then returns and explains that the car went into reverse. A distraught Tom returns shortly thereafter with a large piece of the wrecked BMW. Abigail, Diane and Nick try to lighten the mood by offering a toast to Susan and Josh, but Josh suddenly runs out of the apartment.

Susan finds Josh on the roof. She tries to console him by telling him what she loves about him. Realizing that he made a mistake, Josh tells her that he is really a thirteen-year-old boy from New Jersey who became magically big after making a wish at a carnival. She refuses to believe him and slaps him. Confused and emotional, she then professes her love and leaves. An upset Josh returns to his old neighborhood ("Neighborhood Ballet"). He now realizes that being grown-up is not all that it is cracked up to be; it means having to take responsibility for one's actions ("When You're Big"). Billy enters. He and Josh reconcile and the two head off to find the Zoltar machine.

Josh and Billy find themselves in a nearby warehouse. Searching the cavernous area, Josh eventually finds a Zoltar machine. Susan, whom Josh has called in anticipation of his transformation, arrives. Billy leaves the two alone in private; Susan now realizes that everything Josh has told her about himself is true. She recognizes the Zoltar machine and agrees that it's time to let go — to allow Josh to return to his former self. The two say goodbye to each other, and Josh begins to cry ("We're Gonna Be Fine"). Susan shows Josh the Startraveller Compass ring that he gave her and they promise that they'll never forget one another. Billy returns with a bag of quarters, and Josh inserts one into the machine. He kicks the machine and it comes to life. As Billy and Susan watch, Josh makes his wish and is magically transformed back into a thirteen-year-old boy. He and Billy break into their hip-hop routine. Josh and Susan wave goodbye as Susan exits. Mrs. Baskin enters and embraces Josh as the curtain falls.