In this follow up to Les Quatre Cents Coups (The 400 Blows), Antoine Doinel (Jean-Pierre Leaud) is now aged 18 and working at Phillips packaging records. One day while attending a Berlioz concert he falls head over heels for a beautiful young woman in the audience. After plucking up the courage to talk to Colette (Marie-France Pisier), they soon become good friends, but he is unable to admit his true feelings for her. His infatuation becomes so great that he moves into an apartment across the street from her so he can spy on her, but ultimately his possessiveness only ends up driving her into the arms of another.

This short originally appeared as part of the omnibus film, Love At Twenty, which included also shorts by Renzo Rossellini, Shintaro Ishihara, Marcel Ophuls, and Andrzej Wajda.

After the success of Jules and Jim, Francois Truffaut accepted an invitation from producer Pierre Roustang to take part in an international omnibus film called Love at Twenty. For his short section, Truffaut decided to revive the character of Antoine Doinel from Les Quatre Cents Coups (The 400 Blows).

As in the earlier film, the director drew on events from his own life for much of the story of Antoine and Colette. When he was seventeen years old, he had fallen in love with a girl named Liliana Litvin who he met at the Cinematheque Francaise. He was so taken with her that he moved first to Paris from the suburbs and then into a hotel room directly across from her apartment. Liliana, however, was a beauty with many admirers, and nothing ever came of the young Truffaut’s infatuation. After a failed suicide attempt, he joined the army in an effort to forget her, only to end up deserting after a few months, and, as a result, spending several months in Coblenz military prison.

Reflecting back on Antoine and Colette, Truffaut said, "I did it in a carefree moment: Jules and Jim had just come out and had been very well received, which was why I went to work on Love at Twenty in a really cheerful mood. When Love at Twenty was finished, we realized that it was a melancholy film, sometimes even desperate, and was so without our having sought it, simply because love at twenty is something sad in the way it's out of sync with the adult style of life."