Thesmophoriazusae, or Women at the Thesmophoria, is one of eleven surviving comedy plays by Aristophanes. It was first produced in 411 BC, probably at the City Dionysia. The play's focuses include the subversive role of women in a male-dominated society; the vanity of contemporary poets, such as the tragic playwrights Euripides and Agathon; and the shameless, enterprising vulgarity of an ordinary Athenian, as represented in this play by the protagonist, Mnesilochus. The work is also notable for Aristophanes' free adaptation of key structural elements of Old Comedy and for the absence of the anti-populist and anti-war comments that pepper his earlier work. It was produced in the same year as Lysistrata, another play with sexual themes.

The Thesmophoria was an ancient Greek religious festival, held in honor of the goddess Demeter and her daughter Persephone. It was held annually, mostly around the time that seeds were sown in late autumn – though in some places it was associated with the harvest instead – and celebrated human and agricultural fertility. The festival was one of the most widely celebrated in the Greek world. It was restricted to adult women, and the rites practised during the festival were kept secret. The most extensive sources on the festival are a comment in a scholion on Lucian, explaining the festival, and Aristophanes' play Thesmophoriazusae, which parodies the festival.