The original story was inspired in part by Nora Johnson's own experiences as a schoolgirl, as well as by a real life incident involving singer Tony Bennett and two teenaged fans.
In early 1960s New York City, concert pianist Henry Orient (Peter Sellers) pursues an affair with a married woman, Stella Dunnworthy (Paula Prentiss), while two adolescent private-school girls, Valerie "Val" Boyd (Tippy Walker) and Marian "Gil" Gilbert (Merrie Spaeth), stalk him and write their fantasies about him in a diary. Orient's paranoia leads him to believe that the two girls, who seem to pop up everywhere he goes, are spies sent by his would-be mistress's husband.
In reality, fourteen-year-old Val, the bright and imaginative daughter of wealthy international trade expert Frank Boyd (Tom Bosley) and his unfaithful, snobbish wife Isabel (Angela Lansbury), has developed a teenage crush on Henry after seeing him in concert, and involved her best friend Marian. Although Marian's parents are divorced, Marian lives a relatively happy and stable life in a townhouse in the city with her mother and her mother's also-divorced female friend, while Val, whose parents are still married (albeit unhappily), sees a psychiatrist daily and lives with paid caretakers while her parents travel the world.
Val's parents return for Christmas, and Val becomes concerned that her mother Isabel is having an extramarital affair with a young pianist. Val's interference leads her mother to find and read Val's diary. Isabel chastises Val and seeks out Henry, ostensibly to tell him to stay away from her underage daughter. The cheating Isabel and the womanizing Henry are quickly attracted to each other and begin an affair, which Val and Marian accidentally discover while stalking Henry outside his apartment. Val's devastation and Isabel's attempts to cover up her own behavior cause Frank to figure out what happened. Frank and Isabel separate, while the paranoid Henry flees the country. However, positive changes for Val result as Frank, who unlike Isabel genuinely cares about his daughter, resolves to stop traveling so much and establish a real home where he and Val can spend more time together. In the end, Val and Marian have matured and moved on from fantasy play to makeup, fashion and boys their own age.
This was the first film appearance for both Tippy Walker and Merrie Spaeth.
Filming started in June 1963 and wrapped that October.
The pianist's unusual surname, "Orient", came about because Nora Johnson based the character on Oscar Levant, a real-life concert pianist, raconteur, and film actor on whom she had a crush as a teenager. Since the word "levant" means Orient in French (literally the direction from which the sun rises), the name is a play on words. In the film, several allusions to the pianist's unusual name occur when his two teenage fans put on Chinese conical hats, address their idol as "Oriental Henry," kowtow to an Asian-style altar, and adopt vaguely Japanese-sounding names for themselves.
Spaeth, who was 15 at the time of filming, had no previous acting experience except for a minor role in a school production, and was cast after the head of her school's drama department suggested her to a talent scout. The World of Henry Orient is Spaeth's only film appearance, as she shortly thereafter left acting.
Walker, who was 16 at the time of filming (turning 17 shortly before the film was released), had worked as a model and was suggested to the film's producer by a photographer. According to a 2012 article in The New Yorker by John Colapinto, director George Roy Hill handpicked Walker from hundreds of actresses who auditioned for the role of "Val". The filmmakers were so impressed with her performance that they reshaped the film during editing to focus more on her character, and shot the scene of her walking through a snowy Central Park months after production had wrapped. According to Colapinto, in the 2000s Walker revealed through a series of posts on IMDb that she and Hill fell in love during the filming, and that the relationship lasted throughout most of Walker's senior year in high school, despite the fact that Hill was married with children and, at age 44, was nearly 30 years older than Walker. Walker claimed that the resulting Hollywood gossip made others reluctant to cast her and contributed to her decision to stop acting in the early 1970s.
The World of Henry Orient premiered at Radio City Music Hall on March 19, 1964. It was the official U.S. entry at the 1964 Cannes Film Festival. In 1965 it was nominated for the Golden Globe Award in the category "Best Motion Picture, Musical or Comedy" and for a Writers Guild of America Award for "Best Written American Comedy."
The film was well-received by critics and has an 88% rating at Rotten Tomatoes. In his review for The New York Times, Bosley Crowther wrote that it was "one of the most joyous and comforting movies about teenagers that we've had in a long time".
It was voted one of the Year's Ten Best Films by the National Board of Review in 1964.
A Broadway musical adaptation of The World of Henry Orient called Henry, Sweet Henry, with music and lyrics by Bob Merrill, book by Nunnally Johnson (the father of Nora Johnson), direction by George Roy Hill and choreography by Michael Bennett, opened at the Palace Theatre on October 23, 1967. It starred Don Ameche as Henry Orient, Neva Small as Marian Gilbert, Robin Wilson as Valerie Boyd, Milo Bouton as Mr Boyd, Carol Bruce as Mrs. Boyd and Louise Lasser as Stella. Pia Zadora also appeared in the role of a student. The show ran for 80 performances and closed on December 31, 1967, receiving less than stellar reviews. William Goldman, in his study of the 1967-68 theater year "The Season", claimed that the musical was of high quality but was old fashioned, and "had the misfortune" to open just a week after all the critics "were overcome by Hair," which had a modern sound.
Although the show was not a success, one of its performers, Alice Playten, received a 1968 Theatre World Award, and was nominated for a Tony Award for "Best Featured Actress in a Musical" for playing the role of Kafritz, which was enlarged substantially for the play. In addition, Michael Bennett was nominated for a Tony for "Best Choreography."