Sir Rowland de Bois has recently died, and, according to the custom of primogeniture, the vast majority of his estate has passed into the possession of his eldest son, Oliver. Although Sir Rowland has instructed Oliver to take good care of his brother, Orlando, Oliver refuses to do so. Out of pure spite, he denies Orlando the education, training, and property befitting a gentleman. Charles, a wrestler from the court of Duke Frederick, arrives to warn Oliver of a rumor that Orlando will challenge Charles to a fight on the following day. Fearing censure if he should beat a nobleman, Charles begs Oliver to intervene, but Oliver convinces the wrestler that Orlando is a dishonorable sportsman who will take whatever dastardly means necessary to win. Charles vows to pummel Orlando, which delights Oliver.
Duke Senior has been usurped of his throne by his brother, Duke Frederick, and has fled to the Forest of Ardenne, where he lives like Robin Hood with a band of loyal followers.
Duke Frederick allows Senior's daughter, Rosalind, to remain at court because of her inseparable friendship with his own daughter, Celia. The day arrives when Orlando is scheduled to fight Charles, and the women witness Orlando's defeat of the court wrestler. Orlando and Rosalind instantly fall in love with one another, though Rosalind keeps this fact a secret from everyone but Celia. Orlando returns home from the wrestling match, only to have his faithful servant Adam warn him about Oliver's plot against Orlando's life. Orlando decides to leave for the safety of Ardenne. Without warning, Duke Frederick has a change of heart regarding Rosalind and banishes her from court. She, too, decides to flee to the Forest of Ardenne and leaves with Celia, who cannot bear to be without Rosalind, and Touchstone, the court jester. To ensure the safety of their journey, Rosalind assumes the dress of a young man and takes the name Ganymede, while Celia dresses as a common shepherdess and calls herself Aliena.
Duke Frederick is furious at his daughter's disappearance. When he learns that the flight of his daughter and niece coincides with the disappearance of Orlando, the duke orders Oliver to lead the manhunt, threatening to confiscate Oliver's lands and property should he fail. Frederick also decides it is time to destroy his brother once and for all and begins to raise an army.
Duke Senior lives in the Forest of Ardenne with a band of lords who have gone into voluntary exile. He praises the simple life among the trees, happy to be absent from the machinations of court life. Orlando, exhausted by travel and desperate to find food for his starving companion, Adam, barges in on the duke's camp and rudely demands that they not eat until he is given food. Duke Senior calms Orlando and, when he learns that the young man is the son of his dear former friend, accepts him into his company. Meanwhile, Rosalind and Celia, disguised as Ganymede and Aliena, arrive in the forest and meet a lovesick young shepherd named Silvius who pines away for the disdainful Phoebe. The two women purchase a modest cottage, and soon enough Rosalind runs into the equally lovesick Orlando. Taking her to be a young man, Orlando confides in Rosalind that his affections are overpowering him. Rosalind, as Ganymede, claims to be an expert in exorcising such emotions and promises to cure Orlando of lovesickness if he agrees to pretend that Ganymede is Rosalind and promises to come woo her every day. Orlando agrees, and the love lessons begin.
Meanwhile, Phoebe becomes increasingly cruel in her rejection of Silvius. When Rosalind intervenes, disguised as Ganymede, Phoebe falls hopelessly in love with Ganymede. One day, Orlando fails to show up for his tutorial with Ganymede. Rosalind, reacting to her infatuation with Orlando, is distraught until Oliver appears. Oliver describes how Orlando stumbled upon him in the forest and saved him from being devoured by a hungry lioness. Oliver and Celia, still disguised as the shepherdess Aliena, fall instantly in love and agree to marry. As time passes, Phoebe becomes increasingly insistent in her pursuit of Ganymede, and Orlando grows tired of pretending that a boy is his dear Rosalind. Rosalind decides to end the charade. She promises that Ganymede will wed Phoebe, if Ganymede will ever marry a woman, and she makes everyone pledge to meet the next day at the wedding. They all agree.
The day of the wedding arrives, and Rosalind gathers the various couples: Phoebe and Silvius; Celia and Oliver; Touchstone and Audrey, a goatherd he intends to marry; and Orlando. The group congregates before Duke Senior and his men. Rosalind, still disguised as Ganymede, reminds the lovers of their various vows, then secures a promise from Phoebe that if for some reason she refuses to marry Ganymede she will marry Silvius, and a promise from the duke that he would allow his daughter to marry Orlando if she were available. Rosalind leaves with the disguised Celia, and the two soon return as themselves, accompanied by Hymen, the god of marriage. Hymen officiates at the ceremony and marries Rosalind and Orlando, Celia and Oliver, Phoebe and Silvius, and Audrey and Touchstone. The festive wedding celebration is interrupted by even more festive news: while marching with his army to attack Duke Senior, Duke Frederick came upon a holy man who convinced him to put aside his worldly concerns and assume a monastic life. -Frederick changes his ways and returns the throne to Duke Senior. The guests continue dancing, happy in the knowledge that they will soon return to the royal court.