Ferdinand, the king of Navarre, establishes an oath for his entire court, including his three lords Dumaine, Longaville, and Berowne. The oath forbids anyone from spending time with a woman for three years, in order to spend all that time studying. The oath also mandates that everyone will eat only once a day and sleep only three hours per night. Longaville and Dumaine quickly agree to the oath, but Berowne argues against it, saying that excessive studying is bad. He also informs Ferdinand that the princess of France is set to visit the court on official business. The king says that he will then have to violate his own oath “on mere necessity.” Seeing how easy it is to get out of the oath, Berowne finally agrees to sign it. Ferdinand also tells Berowne that the Spanish musician and singer Armado will be enough entertainment for them for the three-year period of the oath. A constable named Dull enters with Costard and a letter from Armado. The letter says that Armado saw Costard with a woman named Jacquenetta, in violation of the oath of Ferdinand’s court. Costard tries to get out of punishment with some clever wordplay, but the king sentences him to a week of fasting and orders for Armado to be in charge of carrying out this punishment.
Elsewhere, Armado confesses to his page Mote that he is in love with the “base wench” Jacquenetta. This love has made him melancholy, and he asks Mote to name him some “great men” who have also been in love. The page names Hercules and Samson. Dull enters with Costard and Jacquenetta, informing Armado of Costard’s punishment. Armado tells Jacquenetta that he loves her. Dull takes Jacquenetta away and Mote leaves with Costard. Alone on stage, Armado calls love “a devil,” but takes some comfort in the fact that even strong men like Hercules and Samson have been affected by love. He says that he will “turn sonnet” and write out his love.
The princess of France arrives in Navarre with her attendants: Boyet, Katherine, Rosaline, and Maria. Aware of Ferdinand’s oath, she sends the male Boyet ahead to speak with him. Boyet comes back and tells the princess that they are to camp out in the field, as women are not allowed in Ferdinand’s court. Ferdinand arrives with his three lords and apologizes to the princess. While Ferdinand and the princess negotiate over the exchange of the territory of Aquitaine, Rosaline and Berowne flirt by exchanging witty one-liners. Dumaine asks Boyet about Katherine and Longaville asks him about Maria, both clearly infatuated by these two women. The two groups part, and Boyet tells the princess that he thinks Ferdinand is in love with her.
Armado has Mote free Costard so that he can give him a letter to be delivered to Jacquenetta. He gives Costard a coin as remuneration for the favor and Costard mishears him, thinking that the coin is called “a remuneration.” Berowne then finds Costard and gives him a letter to deliver to Rosaline. Berowne bemoans his intense love for Rosaline and refers to it as a plague that Cupid is punishing him with. Meanwhile, the princess goes on a hunting trip with her attendants. Costard finds them and tells them he has a letter for Rosaline. However, he delivers the letter from Armado by mistake. Boyet reads out the over-wrought letter expressing Armado’s love for Jacquenetta. The princess laughs at the ridiculous letter. Maria, Boyet, and Rosaline trade quips back and forth involving romantic puns on hunting terms. Everyone but Costard leaves, and Costard is amazed at their “sweet jests, most incony vulgar wit.”
A schoolteacher named Holofernes, a curate named Nathaniel, and Dull discuss the princess’ hunting trip. Holofernes and Nathaniel alternate English with Latin phrases, which Dull misunderstands, to their amusement. Jacquenetta and Costard enter. Jacquenetta gives Nathaniel a letter that Costard gave her, supposedly from Armado. However, it turns out to be Berowne’s letter to Rosaline, which contains a love poem. Holofernes tells Jacquenetta to bring the letter to Ferdinand. Alone at court, Berowne laments his love for Rosaline. He sees Ferdinand approaching and hides. Ferdinand reads out a poem he has written for the princess. He hears someone coming and hides. Longaville enters and laments his love for Maria, reading a poem he has written for her. He sees that someone is coming and hides, as well. Dumaine enters and describes his love for Katherine. Longaville jumps out and scolds Dumaine for loving Katherine. But then Ferdinand comes out of hiding and chastises both of them. Finally, Berowne comes forward and calls all three of them hypocrites, criticizing them for breaking Ferdinand’s oath. But then, Costard and Jacquenetta enter with Berowne’s letter. Berowne tries to rip up the letter, but Dumaine reads it and sees what it is. Berowne confesses that he is also in love. Jacquenetta and Costard leave, and the king and his lords discuss their beloveds. Ferdinand asks the clever Berowne to reason some justification for their breaking the oath and pursuing their loves. In a long speech full of clever wordplay, Berowne says that the object of the oath was study and that they will learn more from beauty and from being in love than from any books. Ferdinand, Longaville, and Dumaine are persuaded and excitedly go forth to begin courting their respective women. Ferdinand suggests they woo the French women with “some entertainment.”
Holofernes and Nathaniel discuss Armado, and Holofernes criticizes his way of speaking and pronunciation. Armado enters with Costard and Mote. Mote pokes fun at Holofernes and Nathaniel, teasing and outwitting them. Armado asks Holofernes for advice on what show he is to present to the princess on Ferdinand’s behalf. Holofernes suggests the pageant of the Nine Worthies, a presentation of nine famous mythological, Biblical, and historical figures. He casts Armado, Nathaniel, Costard, Mote, and himself in the performance.
The princess and her ladies discuss and laugh at the love letters and gifts they have received from Ferdinand and his lords. Boyet enters and tells them that Ferdinand and his men are planning to come visit them disguised as Russian ambassadors. The princess plans for all the ladies to wear masks and exchange their gifts so that the men mistake their identities. Mote, Ferdinand, Berowne, Longaville, and Dumaine arrive in Russian dress. The men try to get the women to dance, but they refuse, teasing them. The men then attempt to woo the wrong women, misled by the gifts the women have traded with each other. The women continue to tease and mock the men wittily, and they leave disappointed. Soon after, Ferdinand and his lords return without their disguises. Ferdinand tells the princess that she is now welcome in his court, but she says she doesn’t want to make him break his oath. She says that has enjoyed staying in the field and was just visited by a group of Russians, whom Rosaline describes as foolish. Rosaline then hints that the women know the Russians were Ferdinand and his men in disguise. Ferdinand confesses and apologizes. The princess asks Ferdinand to repeat what he had whispered into his lover’s ear when he was in disguise. He does so, and Rosaline says that this is what her lover told her. Ferdinand is confused, but Berowne realizes that the ladies had traded their gifts with each other.
Costard enters and announces that it is time for the performance of the Nine Worthies. Costard appears first as Pompey, and Boyet, Berowne, and Dumaine heckle him. Nathaniel then enters as Alexander the Great and is also teased. Holofernes and Mote enter, Holofernes playing Judas Maccabaeus and Mote playing the young Hercules. The audience continues to heckle and tease the performers. Armado enters as the Greek hero Hector, to more heckling. Costard suddenly announces to everyone that Jacquenetta is pregnant with Armado’s child. Armado is upset and prepares to duel Costard. Just then, though, a messenger named Marcade arrives from France and tells the princess that her father has died. Berowne tells all the actors to leave, and the princess announces that she will leave for France immediately. Ferdinand begs her to stay and avows his love for her. The princess says that she assumed the men’s love was all “pleasant jest and courtesy,” and she didn’t realize how seriously they felt about it. The princess says that she will consider Ferdinand’s suit if he spends a year at “some forlorn and naked hermitage,” while she takes time to grieve. Similarly, Katherine tells Dumaine to wait for a year before continuing to court her. Maria gives Longaville a similar offer, but Rosaline has something else in store for Berowne. She tells him that he must spend a year at a hospital, using his wit to make the seriously ill laugh. Then, he will have a chance with her. The men all agree to these conditions. Berowne comments that their loves have not come to happy endings befitting of a comedy. Armado enters and says that there was supposed to be a song at the end of the performance of the Nine Worthies. All the actors come back to perform the song in two groups, one representing spring and one representing winter. The groups each sing a short song about their respective season, and the play ends.