In the garden of Leonato
The Sicilians welcome home their army, under the generalship of Don Pedro, victorious against the Moors. Hero, daughter of Leonato, Governor of Sicily, hears with pleasure of the success of her beloved Claudio, while her cousin, Beatrice, asks scornfully after the fate of Claudio's best friend Benedick, with whom she wages a constant battle of wits. Hero looks forward to Claudio's return and Beatrice and Benedick trade insults.
When Don Pedro and Claudio ask Benedick if he is ready to follow Claudio's example, he waxes derisive about the charms of marriage, declaring that if they find him taking so foolish a step, they can out a placard on him: "Here you may see Benedick the married man." They resolve to try and make a match between him and Beatrice.
Somarone rehearses his choir in an epithalamium and Benedick continues to reflect on what he considers Claudio's fallen state, from bachelorhood to marriage. Making sure that Benedick is within earshot, Leonato, Don Pedro and Claudio discuss Beatrice's supposed infatuation with him. He determines that he will be in love with Beatrice. Hero and Ursula reflect on the coming of night and the joys of love.
A grand apartment in the Governor's palace
The wedding banquet is in progress. Somarone sings a drunken song in praise of Sicilian wine. Beatrice, who has overheard Hero and Ursula discussing Benedick's supposed love for her, is moved and prepared to admit to herself that she loves him, but when the two meet, they are awkward and tongue-tied.
The wedding of Hero and Claudio is celebrated and the notary reveals the existence of a second contract. After some hesitation Beatrice and Benedick are persuaded to admit their love. Benedick happpily accepts his placard, declaring him Benedick the married man. They sign the contract, though promising that hostilities will resume tomorrow.