The screenplay was written by Dan Greenburg, who wrote the original source novel, Philly. Greenburg appears as the manager of a motel in the film.
Philip "Philly" Fillmore (Eric Brown) is a 15-year-old high school student and the son of a rich businessman in Albuquerque, who has left town on an extended trip during summer break, leaving the young man in the passing care of Nicole Mallow (Sylvia Kristel), a sexy French housekeeper, and Lester Lewis (Howard Hesseman), the family's chauffeur.
Philly becomes infatuated with Nicole. When she spots him peeping into her room, she tells him to close her door. To Philly's utter shock, she means for him to close her door from the inside and then watch her undress. However, it is too much for him when a topless Nicole asks him to touch her breasts. When he objects, she steps back and instead takes off her panties. Philly panics and leaves.
Later on, he is surprised to find her in his father's bathtub. Once again to his amazement, she asks him to join her. At first he objects, but instead she keeps sweet-talking him until he finally gives in. However, he decides to wear swimming trunks. Once in the bathtub, she spoons and kisses him from behind. When she tries to take off his swimming trunks from behind, he insists that she turn off the lights first. But once she reaches for his private area, he again panics and rushes out. She follows him to apologize, kisses him and directly invites him to sleep with her, the sexual element of which he fails to comprehend at first. After they flirt in a movie theater the following day, he gives in but backs down when she reacts without fondness to the notion of marrying him. One day later, she tells him she guesses they can at least date for a while. After they flirt during their first date in a restaurant, they return home and have sex.
Nicole is revealed as an illegal alien; Lester is using this secret to blackmail her into helping him in a larger blackmail scheme against Philly. Lester intends that Nicole seduce Philly then fake her own death during intercourse. Lester would then "help" the panicked Philly to secretly bury Nicole. Her body would later disappear, and a note would order Philly to steal $10,000 from his father to prevent exposure of his role in Nicole's "death".
When Nicole has second thoughts, Lester threatens to also expose her as a child molester. Nicole has truly fallen in love with Philly, and she reveals the truth to him. Philly convinces his tennis coach (Ed Begley, Jr.) to pose as a police detective and intimidate Lester with questions about Nicole's disappearance. Lester panics but is caught with the money before he can flee the country. Nicole and Philly return the money to the safe, but they decide not to expose Lester's treachery. In turn, he reluctantly decides not to expose Nicole's illegal alien status nor her acts of child molestation, knowing that Philly could easily expose his attempted embezzlement scheme to his father and the police, and as a result, he keeps his job.
Nicole fears that Philly's father will eventually discover their affair, and decides to leave. Before she does, she and Philly have intercourse one last time. Summer Vacation ends and Philly returns to high school, thanks his teacher for advising him to pursue girls whose age is more appropriate for him and, in order to "discuss" this matter more closely, successfully asks her out to dinner.
Famous artists included:Air Supply: "Lost In Love"Eric Clapton: "Next Time You See Her"John Cougar: "I Need a Lover"Rod Stewart: "Hot Legs" "Tonight's The Night," and "You're in My Heart"Willie Nile: "That's The Reason"Randy VanWarmer: "Just When I Needed You Most"Earth, Wind and Fire: "Fantasy"
Dan Greenburg wrote the film's screenplay, which he adapted from his own 1969 novel Philly. Producer R. Ben Efraim would produce a number of additional Private... movies over the next decade, including another cult favorite, 1983's Private School (which features Sylvia Kristel in a bit role), and two in-name-only sequels to Private Lessons in 1993 and 1994.
During the bedroom striptease, Judy Helden performed as the body double for Sylvia Kristel.
The film was sponsored primarily by Jack Barry & Dan Enright Productions, even though its two chief producers, Jack Barry and Dan Enright, were better known for their game shows on television, of which Barry was the on-camera host and Enright the primary behind-the-scenes producer. The company's primary announcer at the time, Jay Stewart, provided the narration for one of the movie trailers for the film. Later TV commercials were narrated by future Disney trailer announcer Mark Elliot.
The film was also the first picture for Jensen Farley Pictures (a subsidiary of Sunn Classic Pictures), a movie studio founded by Rayland Jensen (founder of Sunn Classic Pictures) and his fellow employee, Clair Farley. Sunn, initially a subsidiary of the Schick razor company, would be sold to Taft Broadcasting in 1980, shortly before this film's release. Jensen Farley Pictures was created after the sale to Taft, and one of the company's early releases was a film produced by Taft, The Boogens, initially planned for release through Sunn. Jensen Farley would later release another sex comedy whose selling point was the promise of a young man coupled with an alluring older woman, Homework with Joan Collins.
Director Alan Myerson and the cinematographer he hired, Jan de Bont, shot their principal photography for the film in Arizona and New Mexico.
In 1985, the film was made in Italian as "Il peccato di Lola," starring Donatella Damiani.