Dates

The play was probably written between 1598 and 1599 within a few years of The Merchant of Venice. There is no mention of Much Ado About Nothing in Frances Meres' 1598 compilation Palladis Tamis but it does list Love's Labour's Won, thought by some to be an alternative title for the play. By 1600, when the first Quarto edition of the play was published, Much Ado About Nothing was said to have been 'acted publicly several times'. Will Kemp, the comedian who is known to have played Dogberry, left the Lord Chamberlain's Company during 1599. 

Sources

The Hero-Claudio plot is very old and appears in Greek, Spanish and Italian romances, notably in Ariosto's Orlando Furioso which was translated by Sir John Harington in 1591. The story was re-worked by Bandello in his 1554 Novella, as the tale of Sir Timbreo and Fenicia, which also featured the characters Piero King of Aragon and Lionato of Messina. Spenser's The Fairie Queene could also have been an influence, so it is likely that Shakespeare drew on many of these works.

The Beatrice and Benedick plot is thought to be largely Shakespeare's own invention. However, it is possible that Shakespeare was aware of Sir Thomas Hoby's 1561 translation of Castiligione's The Courtier. The English text includes a remark that some fell in love 'onely for that they heard say the opinion of many was that they loved together'. The plays of John Lyly also featured witty couples who scorn love but then succumb to Cupid's darts. The characters of Dogberry, Verges and the Watch appear to be unique Shakespeare creations.