Identical twins Susan Evers and Sharon McKendrick (Hayley Mills) meet at Miss Inch's Summer Camp for Girls, unaware that they are sisters. Their identical appearance initially creates rivalry, and they continuously pull pranks on each other, which ultimately leads to the camp dance being crashed by their mischief. As punishment, they must live together in the isolated "Serendipity" cabin (and eat together at an "isolation table") for the remainder of their time at summer camp. After finding out that they both come from single parent homes, they soon realize they are twin sisters and that their parents, Mitch (Brian Keith) and Maggie (Maureen O'Hara), divorced shortly after their birth, with each parent having custody of one of them. The twins, each eager to meet the parent she never knew, switch places. They drill each other on the other's behavior and lives, and Susan cuts Sharon's hair into the same style as hers. While Susan is in Boston, Massachusetts masquerading as Sharon, Sharon goes to Carmel, California pretending to be Susan.
Sharon telephones Susan in Boston with news that their father is planning to remarry, and that their mother needs to be rushed to California to stop the wedding. In Boston, Susan reveals to her mother the truth about the switched identities and the two fly to California.
In California, the twins (with mild approval from their mother) scheme to sabotage their father's marriage plans. Mitch's money-hungry - and much younger - fiancée Vicky Robinson (Joanna Barnes) receives rude, mischievous treatment from the girls and some veiled cattiness from Maggie. One evening, the girls recreate their parents' first date at an Italian restaurant with a gypsy violinist. The former spouses are gradually drawn together, though they quickly begin bickering over minor things and Vicky.
To delay Maggie's return to Boston with Sharon, the twins dress and talk alike so their parents are unable to tell them apart. They will reveal who is who only after returning from the annual family camping trip. Mitch and Maggie reluctantly agree, but when Vicky discovers and consequently objects to the plan of them spending alone time together in the woods, Maggie tricks her into taking her place instead (knowing full well that she's not made for 'the great outdoors', which might very well prove her undoing). The girls effect the coup de grâce; Vicky spends her time swatting mosquitoes (being tricked by the girls to use sugared water instead of mosquito repellent) and being awakened in terror by two bear cubs licking honey off her feet which the twins had previously placed there. Exasperated, Vicky finally has a shouting tantrum destroying everything in her path and culminating in angrily slapping one of the girls, leaving Mitch with a whole new-found view of her. When she runs off to escape back to the city in a great huff, Mitch seems none too worried to be rid of her. When Mitch and the girls return from the trip, Maggie greets them with a sumptuous home-cooked meal, and Mitch is immediately reminded and recaptured by her charms. They are soon reminiscing about their past and Mitch admits that he's missed her dearly which leads to them embracing with a kiss. They admit to each other that neither want nor need grow old alone, which is slowly creeping up on them; they have no more time to lose. With this they rekindle their love, and the two remarry in the final scene, with the twins, members of the wedding party, elated their plan worked out exactly as they'd hoped.Hayley Mills as Sharon McKendrick/Susan Evers
Brian Keith as Mitch Evers
Maureen O'Hara as Maggie McKendrick
Joanna Barnes as Vicky Robinson
Charlie Ruggles as Charles McKendrick
Cathleen Nesbitt as Louise McKendrick
Una Merkel as Verbena
Leo G. Carroll as Reverend Dr. Mosby
Linda Watkins as Edna Robinson
Ruth McDevitt as Miss Abbey Inch
Crahan Denton as Hecky
Nancy Kulp as Miss Grunecker
Susan Henning as Susan/Sharon double
Richard and Robert Sherman provided the songs, which, besides the title song "The Parent Trap", includes "For Now, For Always", and "Let's Get Together". "Let's Get Together" (sung by Annette Funicello) is heard playing from a record player at the summer camp; the tune is reprised by the twins when they restage their parents' first date and that version is sung double-tracked by Hayley Mills. (Hayley's own single of the song, credited to "Hayley Mills and Hayley Mills," reached #8 on the US charts.) The film's title song was performed by Tommy Sands and Annette Funicello, who were both on the studio lot shooting Babes in Toyland at the time.
The film was nominated for two Academy Awards: one for Sound by Robert O. Cook, and the other for Film Editing by Philip W. Anderson. The film and its editor, Philip W. Anderson, won the inaugural 1962 Eddie Award of the American Cinema Editors.
In 1961 a comic book version of the film was published, adapted and illustrated by Dan Spiegle.
The film was theatrically re-released in 1968 and earned $1.8 million in rentals.
The Disney Studios produced three television sequels The Parent Trap II (1986), Parent Trap III (1989) and Parent Trap: Hawaiian Honeymoon (1989). The original was remade in 1998 starring Lindsay Lohan, Dennis Quaid and Natasha Richardson.
In India, there have been several films inspired by The Parent Trap. In 1965, a Tamil language version of the story called Kuzhandaiyum Deivamum, starring Kutty Padmini was released. The following year, it was remade into Telugu as Leta Manasulu also starring Kutty Padmini. A Hindi version Do Kaliyaan starring Neetu Singh in the double role was made in 1968. The 1987 film Pyar Ke Kabil also has a similar storyline, as does the 2001 film Kuch Khatti Kuch Meethi which has Kajol playing the double role of 23-year-old twins.
The film was released on a 2-disc special edition DVD in 2005.