A "dark" comedy in five acts, first produced around 1604-05 and published in the First Folio of 1623 from a transcript of imperfect foul papers. The play examines the nature of mercy and justice, proposing that a good government is one that is flexible and based on common sense. Shakespeare adapted the story from Epitia, a drama by Italian dramatist Giambattista Giraldi (also called Cinthio) and from a two-part play by George Whetstone entitled Promos and Cassandra (1578).

Shakespeare's Measure for Measure can be seen as an early account of sexual harassment. While the issue of women's rights had hardly been explored at the time the play was first performed, Measure for Measure touches on issues of sexuality, independence, and the objectification of women. Despite these serious issues, the play is considered a comedy, and the story it tells is filled with amusing characters as well as broad sociological questions.

Vincentio, Duke of Vienna, decides to take a sabbatical, appointing his deputy, Angelo, to rule as his proxy while the Duke is gone. The Duke, it seems, has grown lax in the enforcement of laws regarding wanton or unchaste behaviour, and has given Angelo his powers for two specific reasons: a) the Duke does not want to seem a bad man, and b) someone has to accept the unpleasant and unpopular task of being stricter. Angelo is a zealous man, and the Duke feels he is perfect for the task. In the meantime, the Duke secretly remains in town disguised as a friar in order to keep an eye on things from the people's point of view.

The plot centres on the fate of Claudio, who Lord Angelo arrests. As the temporary leader of Vienna. Angelo is strict, moralistic, and unwavering in his decision-making; He decides there is too much freedom in Vienna. Taking it upon himself to rid the city of all brothels and any unlawful sexual activity, though laws against these behaviours and institutions already exist, and Angelo simply decides sterner enforcement is required. Claudio is arrested for impregnating Juliet, his lover, before they were married. Although they were engaged and their sexual intercourse was consensual, Claudio is sentenced to death in order to serve as an example to the other Viennese citizens.

Isabella, Claudio's sister, a novitiate is about to enter a nunnery when her brother is arrested. She is unfailingly virtuous, religious, and chaste. When she hears of her brother's arrest, she goes to Angelo to beg him for mercy. He refuses, but suggests that there might be some way to change his mind. When he propositions her, saying that he will let Claudio live if she will yield her virginity to him, she is shocked, and immediately refuses, her chastity, and honour are her life. She later relates her tale to Claudio, who, understandably, is more willing trade his sister's virtue for his life. Also in the jail, the Duke (in disguise) eavesdrops upon the conversation and sets into motion a plot to save both Claudio and Isabella from their predicament.

Isabella is, in a way, let off the hook when the Duke, dressed as a friar, intervenes. He tells her that Angelo's former lover, Mariana, was engaged to be married to him, but he abandoned her when she lost her dowry in a shipwreck. The Duke forms a plan by which Isabella will agree to have sex with the Angelo, but when the moment comes, Mariana will switch places in the dark with Isabella (the bed trick of All's Well That Ends Well being used again). The next morning, Angelo will pardon Claudio and be forced to marry Mariana according to the law.

Everything goes according to plan, except that Angelo does not pardon Claudio, fearing revenge. When the Duke gets this news, he persuades the jailer to substitute another condemned man for Claudio and to carry out the execution "as planned." All he tells Isabella is that she has been betrayed by Angelo, and she should seek justice from the Duke (who is soon expected to return).

The provost and the Duke send him the head of a dead pirate, claiming that it belonged to Claudio, and Angelo believes that his orders were carried out. Isabella is told that her brother is dead, and that she should submit a complaint to the Duke, who is due to arrive shortly, accusing Angelo of immoral acts.

With that, the Duke abandons his disguise as a friar to make his entrance into Vienna. Saying that he will hear all grievances immediately, Isabella tells her story, and the Duke pretends not to believe her. However Angelo thinks he is cornered. At first he charges Isabella with lying and lays blame with the secret friar (the Duke's disguised alter-ego). When the Duke is revealed as the friar, Angelo can do nothing but throw himself on the mercy of the Duke and Isabella. Claudio is revealed to be alive, Mariana pleads for Angelo's life, and the Duke orders that Angelo should marry Mariana and Claudio should marry Juliet. The Duke makes his own arrangements to be married with Isabella.

Measure for Measure has been oft criticised for its unsatisfying resolution and logical gaps. Why, for instance, should Isabella agree to the Duke's plan when it would force Angelo and Mariana to commit the same crime as Claudio and Juliet, of which she does not approve? The Duke pardons everyone at the conclusion of the play, including Angelo, who is sentenced only to marriage. Isabella presumably leaves the nunnery to marry the Duke, though she never actually agrees to the proposal.

The female characters in Measure for Measure are unusually weak for Shakespeare. The men take complete control of the plot, while the women simply follow along. The major decision facing Isabella is avoided, though it presents a particularly difficult dilemma considering Isabella's desire to be a nun.

Measure for Measure did not achieve great popularity until recently. Perhaps it was written ahead of its time, during an era when the answers to the questions posed by Shakespeare seemed obvious. Today, however, Measure for Measure seems to raise central issues of sexuality, familial loyalty, morality, and religion.