Boccara recorded the song in five languages: French, English, German, Spanish, and Italian.

"Un jour, un enfant" was written by composer Emil Stern and lyricist Eddy Marnay.

[2] On 29 March 1969, the Eurovision Song Contest was held at the Teatro Real in Madrid hosted by Televisión Española (TVE), and broadcast live throughout the continent.

Boccara performed "Un jour, un enfant" fourteenth on the night, following Germany's "Primaballerina" by Siw Malmkvist and preceding Portugal's "Desfolhada portuguesa" by Simone de Oliveira.

[3] At the close of voting, the song had received 18 points, the same number of points as Spain's "Vivo cantando" by Salomé, the United Kingdom's "Boom Bang-a-Bang" by Lulu, and the Netherlands's "De troubadour" by Lenny Kuhr.