Private Lives is a 1930 comedy of manners in three acts by Noël Coward. It concerns a divorced couple who, while honeymooning with their new spouses, discover that they are staying in adjacent rooms at the same hotel. Despite a perpetually stormy relationship, they realise that they still have feelings for each other. Its second-act love scene was nearly censored in Britain as too risqué. Coward wrote one of his most popular songs, ‘Someday I'll Find You’, for the play.

After touring the British provinces, the play opened the new Phoenix Theatre in London in 1930, starring Coward, Gertrude Lawrence, Adrianne Allen and Laurence Olivier. A Broadway production followed in 1931, and the play has been revived at least a half-dozen times each in the West End and on Broadway. The leading roles have attracted a wide range of actors: among those who have succeeded Coward as Elyot are Robert Stephens, Richard Burton, Alan Rickman and Matthew Macfadyen, and successors to Lawrence as Amanda have included Tallulah Bankhead, Elizabeth Taylor, Joan Collins, Elaine Stritch, Maggie Smith, Penelope Keith and Lindsay Duncan. Directors of new productions have included John Gielgud, Howard Davies and Richard Eyre. The play was made into a 1931 film and has been adapted several times for television and radio.

Coward was in the middle of an extensive Asian tour when he contracted influenza in Shanghai. He spent the better part of his two-week convalescence sketching out the play and then completed the actual writing of the piece in only four days. He immediately cabled Gertrude Lawrence in New York to ask her to keep autumn 1930 free to appear in the play. After spending a few more weeks revising it, he typed the final draft in The Cathay Hotel in Shanghai and sent copies to Lawrence and his producer and manager, John C. Wilson, with instructions to cable him with their reactions.

Coward received no fewer than 30 telegrams from Lawrence about the play. She first said that she had read the play and there was "nothing wrong with it that can't be fixed." Coward "wired back curtly that the only thing that was going to be fixed was her performance." Lawrence was indecisive about what to do about her previous commitment to André Charlot. Coward finally responded that he planned to cast the play with another actress. By the time he returned to London, he found Lawrence not only had cleared her schedule but was staying at Edward Molyneux's villa in Cap-d'Ail in southeastern France learning her lines. Coward joined her, and the two began rehearsing the scenes they shared.

At the end of July they returned to London where Coward began to direct the production. Coward played the part of Elyot Chase himself, Adrianne Allen was his bride Sibyl, Lawrence played Amanda Prynne, and Laurence Olivier was her new husband Victor. Coward wrote Sibyl and Victor as minor characters, "extra puppets, lightly wooden ninepins, only to be repeatedly knocked down and stood up again." He later insisted, however, that they must be credible new spouses for the lead characters: "We've got to have two people as attractive as Larry and Adrianne were in the first place, if we can find them."

Rehearsals were still under way when the Lord Chamberlain took exception to the second act's love scene, labelling it too risqué in light of the fact the characters were divorced and married to others. Coward went to St. James's Palace to plead his case by acting out the play himself and assuring the censor that with artful direction the scene would be presented in a dignified and unobjectionable manner. Coward repeats one of his signature theatrical devices at the end of the play, where the main characters tiptoe out as the curtain falls – a device that he also used in Present Laughter, Hay Fever and Blithe Spirit.

The play contains one of Coward's most popular songs, "Some Day I'll Find You" (sometimes printed as "Someday I'll Find You"). The Noël Coward Society's website, drawing on performing statistics from the publishers and the Performing Rights Society, ranks it among Coward's ten most performed songs.

Following a brief courtship, Elyot and Sibyl are honeymooning at a hotel in Deauville, France, although her curiosity about his first marriage is not helping his romantic mood. In the adjoining suite Amanda and Victor are starting their new life together, although he cannot stop thinking of the cruelty Amanda's ex-husband displayed towards her. Elyot and Amanda, following a volatile three-year-long marriage, have been divorced for five years, but they now discover that they are sharing a terrace while on their honeymoons with their new and younger spouses. Elyot and Amanda separately beg their new spouses to leave the hotel with them immediately, but both new spouses refuse to cooperate and each storms off to dine alone. Realising they still love each other and regretting having divorced, Elyot and Amanda abandon their spouses and run off to Amanda's flat in Paris.