The play opens with the King, Berowne, Longaville and Dumain putting in writing what they've already agreed to do: study for three years, abstain from women, sleep little, and eat less. While Berowne is unwilling, his loyalty to the King convinces him. It looks like the four will enjoy their time in peace, with entertainment provided by Armado.
Enter the Princess, with her beautiful and intelligent ladies-in-waiting. The men don't have a chance. While the King denies them access to the court in order to keep his oath, he is head-over-heels for the Princess.
Hijinks and letter-writing ensue, and the men find out about each other's loves. They break their oaths and prepare an onslaught of wooing. The women reject and tease them.
The women haven't made any commitments yet, but everyone's cozily watching a silly play devised by Armado and Holofernes. Marcade enters with the news that the King of France has died. Wherever these romances were heading, they're not heading there now – not yet, anyway. The Princess has to think about returning to France and assuming the throne.
Slightly insensitively, the King presses the Princess. She protests that the women only flirted for fun. When the men argue that they are serious, the women challenge them to prove it by waiting for a year.
The men agree to wait for the women. Armado enters with the news that he has committed himself to Jaquenetta for the next three years.
With the uncertain promise of future conjugal bliss, the lovers enjoy the Song of Winter and Spring.