Based on a novel by Jean Webster previously filmed in 1919, 1931, and in 1935 as Curly Top, a rich businessman sees an orphan in Paris and sends her to a girls college anonymously, but later he falls in love with her.
Jervis Pendleton III (Fred Astaire) plays drums in jazz. Griggs (Fred Clark) answers the phone and says the State Department wants his decision about going to France. Jervis tells him to flip the record, and he dances to “History of the Beat.” Jervis says they are going.
On a road to Paris, their car gets stuck in a ditch. Jervis says he is going up the road, and at a gate he asks for a telephone. A boy lets him in the house, and he sees Julie Andre (Leslie Caron) speaking English to children and serving lunch. An older woman says they have no telephone, and he asks about a garage. Julie sings “C-A-T Spells Cat.” Jervis borrows an old car, and with Griggs just makes it to the American embassy before the car collapses.
Jervis asks the Ambassador Alex Williamson (Larry Keating) how he can adopt an orphan. When he finds out she is 18 years old, the Ambassador balks. Jervis suggests he could anonymously send her to Walston College in Massachusetts.
Julie gets the letter from the embassy about going to college. She is happily surprised and learns she only has to write him a letter each month. Children see Jervis and his long shadow before he drives away. Julie asks them to describe him, and they say he is old and call him “Daddy Long Legs.” Julie thinks about him and puts the last child to bed.
Julie sees New York City from a plane and takes a train and a taxi to the college. The women students welcome her and sing “Welcome Egghead.” She meets Sally McBride (Charlotte Austin) and her roommates. Two large trunks arrive with new clothes for her. Julie writes a letter thanking her guardian.
Alicia Pritchard (Thelma Ritter) reads her letter aloud to Griggs, who tells her to put it in a new file. The file gets thick, but Julie gets no letter in response. Griggs reads a letter aloud to Alicia. Griggs tells Jervis that his sister-in-law Gertrude Pendleton called about redecorating his house. He gives his permission to Griggs. Alicia reads a letter aloud that complains he is not acting like a father; she asks for at least one letter. Griggs narrates a short letter, and Alicia says a person is not a corporation but has feelings. Jervis is dictating a letter about his airline. Griggs tells him his behavior is reprehensible in ignoring the girl in college. Griggs has Alicia show him the file of letters. Griggs says she is in love with Jervis because he let her stay on his farm during the summers. Griggs says his niece Linda Pendleton is her roommate. Griggs says she is grateful and suggests he read the letters. Jervis sits down to read them.
In one letter she assumes he is a Texas millionaire. Jervis dances in cowboy boots and hat. Then she wonders if he is an international playboy, and he ignores several beautiful women. In a fantasy he dances with Julie on a street with shops. He plucks a star from the sky and hands it to her.
Jervis calls his sister-in-law Gertrude Pendleton (Kathryn Givney) and says he is planning to visit his niece Linda. Ray Anthony (himself) and his band play at the school dance. Gertrude introduces Jervis to Linda Pendleton (Terry Moore). He sees Julie, who dances with Jimmy McBride (Kelly Brown). Sally introduces herself to Jervis and dances with him. Julie tells Jervis her next dance is his, but he suggests they go outside. She shows him a statue of his grandfather. He asks about her relatives, but she says they all died. She says she has a guardian who is bald and walks with a cane. She says she plans to live with him after she gets out of college. He asks why he never comes to see her, and she says he does not care. Jimmy tells Julie they missed a dance, and he takes her back in. The Pied Pipers sing “Slewfoot.” Jervis is pushed and starts dancing with Julie.
Griggs comes into the office and finds Jervis singing “Dream” to a record. He asks Griggs to send the record to Julie. Jervis reads the letter from Julie, who writes that Jimmy lost his chance to go to South Africa as a mining engineer. Jervis asks Griggs if they can help him work somewhere out of the country. Griggs suggests their tin mines in Bolivia.
Julie gets a telegram inviting her and Linda to New York. Jervis meets Julie at the airport, and she says that Linda could not come. He takes her to a nice hotel, and he invites her to dinner. They dine on her balcony, and they talk about his former loves. She thinks he will never marry. He sings “Something’s Gotta Give,” and they dance. After going out all night, he says goodnight at her door and takes a ride on a cart. The ambassador moves into the room next door.
Jervis shows a diamond ring to Griggs and Alicia, and he buys it. Jervis has breakfast with Julie, and the ambassador Alex hears their conversation. He calls her room and tells Jervis that he is contemptible. Jervis tells Julie he is going to see a friend, and he goes next door. Alex asks him what he is doing in her suite; he suspects the worst. Jervis says she knows him only as her roommate’s uncle. Alex learns that Jervis got her boyfriend sent to his mines in Bolivia. Jervis admits he is in love with her and says it is insane. Jervis decides not to go back to her room and calls her that he has business and may go abroad. She says she is disappointed, and they say goodbye.
Julie finds her roommates packing, and they discuss how Uncle Jervis has been traveling from city to city. Julie looks at the clippings of Jervis. She writes a desperate letter to Daddy Long Legs and asks to see him for advice. In a fantasy she is a ballet dancer in Paris. She rehearses, and Jervis watches her. She runs and is back at the hotel. In a room she sees young men at tables and then Jervis with two women. She dances seductively with the young men, but Jervis ignores her and becomes someone else. She finds herself dressed as a clown and dances with circus performers. Three men have very long legs.
Julie wakes up, and Linda offers to mail her letter. Alicia gets the letter and tells Griggs he is so ill that they have to cable Jervis to come home. Griggs says she will have a trust fund.
Julie graduates, and Alicia sees her receive her diploma. Alicia congratulates Julie in her room and says she is going to take her to see Daddy Long Legs. In the office Jervis asks Griggs if she is coming there today. Jervis tells Griggs that he has to be Daddy Long Legs. Linda comes in and asks for Jervis. Linda asks Griggs to leave, and she tells Jervis she is in love and wants to get married; but her mother does not approve. Linda asks Jervis to talk to her mother. Linda says she is going to marry Jimmy McBride. Jervis is happy and offers to pay for the wedding. He asks about Julie, and Linda says she is very unhappy.
In a cab Alicia tells Julie that she is expected. Jervis finds Julie in the museum. A tour guide tells her to stay with the group. She sees Jervis smiling, and she asks if he knows her guardian. She realizes that he is very wealthy. He says he has to ask her guardian’s permission to ask her to marry him. They dance. Griggs asks Alicia to dance, but she suggests a drink instead.
This romantic musical provides a pleasant fantasy for older men who would like to marry a beautiful young woman. The young woman is grateful for the financial assistance and falls in love with her sugar daddy, who turns out to be charming and a good dancer.