Dates

Measure for Measure was originally published in the First Folio of 1623, with the first recorded performance listed as part of James I's Christmas celebrations on 26 December 1604. For this reason, it's usually dated as having been written in 1604 or late 1603, under the reign of the new king.

Although recognised in the First Folio onwards as a comedy, the dark themes and tone of Measure for Measure means it is often classified as one of Shakespeare's problem plays.

Sources

While there were real life stories that mirrored the plot of Measure for Measure very closely, it is believed that Shakespeare took much of his inspiration from two written sources.

The first was Epitia's story from Hecatommithi, a collection of tales by Italian writer Cinthio published in 1565. We know that Shakespeare read this as it was a source for Othello, which was probably also written around 1604. Cinthio tells a similar story to Shakespeare, but the differences make it a tragedy, not a comedy: Epitia sleeps with her abuser, only to find he has already executed her brother (although he did survive in a later version).

Shakespeare's second source was George Whetstone’s 1578 drama Promos and Cassandra. Whetstone was also inspired by Cinthio, but added some comic elements into his narrative, including the Mistress Overdone subplot, moving it closer to the play we now know. However, Shakespeare still made major changes to the plot, crucially in the use of the 'bed trick' to keep Isabella chaste and leaving Mariana to become Angelo's wife.