I.A.L. Diamond co-wrote many Billy Wilder films beginning with Love in the Afternoon. Their partnership became one of the most productive writer-director collaborations in American cinema, lasting from 1957 through Wilder's later career.
Love in the Afternoon, released in 1957, starred Gary Cooper, Audrey Hepburn, and Maurice Chevalier. Wilder and Diamond based the screenplay on Claude Anet's 1920 novel Ariane, jeune fille russe. The film introduced the pair's shared style of combining romantic plots with irony, sexual tension, and sharply timed dialogue.
Diamond and Wilder ultimately collaborated on twelve screenplays. Their best-known films include Some Like It Hot, The Apartment, Irma la Douce, Kiss Me, Stupid, The Fortune Cookie, Avanti!, and Fedora. The Apartment was especially important: the pair won Academy Awards for Best Picture and Best Original Screenplay, while Wilder also won Best Director.
Diamond's initials are sometimes written with different punctuation, such as I. A. L. Diamond, but these forms refer to the same writer. He was born Ițec Domnici in Romania and later became a major Hollywood screenwriter.