Set in the titular seaside town of Rochefort, the story follows twin sisters Delphine (Catherine Deneuve), a ballet instructor, and Solange (Françoise Dorléac), a music teacher. Both long to start a new life outside of Rochefort and to hopefully find true love. Throughout the film, the sisters' stories intertwine with those of a number of other characters:
- Maxence (Jacques Perrin): A sailor about to be demobilized from the navy, as well as a lovesick poet and painter, longing to find his one true love.
- Étienne (George Chakiris) and Bill (Grover Dale): Two slick but kind carnies who arrive with the fair. When their two female dancers quit at the last minute, the two hire Delphine and Solange to perform for them, in exchange for the chance to leave with them for Paris.
- Yvonne (Danielle Darrieux): Delphine and Solange's mother, who owns a café in the middle of town.
- Simon Dame (Michel Piccoli): Yvonne's former fiancee, who just opened a music shop in town, unbeknownst to Yvonne.
- Andy Miller (Gene Kelly): A charming American colleague of Dame's.
All of them repeatedly cross paths until finally coming together, and the twin sisters depart for Paris with their newfound true loves.
The second collaboration between Jacques Demy and Michel Legrand, following The Umbrellas of Cherbourg. Though not as well-remembered as that film, it was a big success upon release, and earned an Academy Award nomination for Best Original Score (Original or Adaptation).
Catherine Deneuve and Françoise Dorléac were Real Life sisters. Sadly, Dorléac was killed in a car accident shortly after the film was released.
The Young Girls of Rochefort provides examples of:
- Always Identical Twins: Averted. Solange and Delphine are not identical twins. Yvonne lampshades that they do not look like each other.
- Annoying Younger Sibling: Solange and Delphine are occasionally irritated by their younger brother Boubou's misbehaviour.
- Coordinated Clothes: the twins, Delphine and Solange, wear coordinated clothes throughout the whole movie.
- Contrived Coincidence:
- Solange asks the help of Simon Dame, who happens to be the former lover of her mother.
- Solange bumps in the street into Andy Miller, who happens to be the musician she tries to get in touch with.
- Maxence dreams of his soulmate and he paints her portrait, which looks like Delphine (who Maxence has never met). He shows the painting's at Guillaume Lancien's gallery. Guillaume happens to be Delphine's ex-boyfriend.
- Excuse Plot: Jacques Demy considered the movie's plot ancillary to the fabulous song and dance numbers.
- "I Am" Song: "We Travel from Town to Town" for the carnies Ètienne and Bill.
- "I Want" Song: Most every main character gets one of these.
- "A Pair of Twins" - Delphine and Solange tire of teaching ballet and music lessons, respectively, and long to find their ideal love and the chance to start a new life outside of Rochefort. Also counts as an "I Am" Song.
- "Maxence's Song" - Maxence longs to find his ideal woman.
- "Andy's Song" - Andy is desperate to find the girl (Solange) whose concerto captivated him so greatly.
- Lady in Red: Solange and Delphine wear very flashy red dresses (backless and with a slit at the side) for their number at the fair. Solange lampshades it by wondering if the dresses will make them look like whores.
- Love at First Sight: Solange and Andy.
- Love Before First Sight: Delphine and Maxence never meet until the very end of the film, but they're each other's ideal, so they're in love.
- Luke, You Are My Father: Simon Dame is Boubou's father. He did not know he had a son.
- Minor Flaw, Major Breakup: Yvonne dumped Simon Dame because he has an unfortunate name.
- Meaningful Name: Guillaume Lancien (litteraly the former one in French) is Delphine's former boyfriend.
- Meet Cute: Solange meets Andy Miller because Boubou throws away his schoolbag, she has to pick its content up and he proposes to help as he passes by.
- One Degree of Separation:
- Delphine is Solange's sister, Maxence's soulmate, Étienne and Bill's employee, Yvonne's daughter and Guillaume Lancien's ex-boyfriend.
- Solange is Delphine's sister, Étienne and Bill's employee, Yvonne's daughter, Simon Dame's customer and Andy Miller's soulmate.
- Maxence is Yvonne's customer and Delphine's soulmate. He shows his paintings at Guillaume Lancien's gallery.
- Étienne and Bill are Delphine and Solange's employers and Yvonne's customers.
- Yvonne is Delphine and Solange's mother, Simon Dame's former lover and she owns a bar where Maxence, Étienne and Bill are customers.
- Simon Dame owns a music shop where Solange is a customer, he is the former lover of Yvonne and an old friend of Andy Miller.
- Andy Miller is Solange's soulmate and Simon Dame's old friend.
- Guillaume Lancien is Delphine's ex-boyfriend and he shows Maxence's paintings in his gallery.
- Shout-Out: Solange at one point refers to Bill and Etienne as Jules and Jim. In a more meta touch, during one musical number the Garniers suggest using the music of Michel Legrand, who wrote the music for this very film (along with others from Demy).
- Small Town Boredom: Delphine and Solange long for love and life outside of Rochefort.
- The Song Remains the Same: Inverted. When released in the United States, the film was dubbed into English, but all the musical numbers were filmed again with the cast mouthing the English lyrics.
- Unfortunate Names: Simon Dame (meaning lady in French). To the point that Yvonne left him because she found his name too ridiculous (not that she does not regret).
- The 'Verse: As with many of Demy's films post-Lola, the characters in this film apparently know those from the previous film; Dutrouz mentions that he knows a hairdresser from Cherbourg named Aimé who married a widow from Nantes named Desnoyers (who was played by Elina Labourdette in Lola).