Così fan tutte, ossia La scuola degli amanti (Thus Do They All, or The School For Lovers) K. 588, is an opera buffa by Wolfgang Amadeus Mozart. The libretto was written by Lorenzo da Ponte.
Così is one of the three Mozart operas for which da Ponte wrote the libretto. (The title is often shortened to Così in the English-speaking world.) The other two da Ponte-Mozart collaborations were Le nozze di Figaro and Don Giovanni.
Così was written and composed at the suggestion of the Emperor Joseph II. The libretto was originally intended to be set to music by Mozart's contemporary Antonio Salieri but Salieri only completed parts of the first act and then broke off work on the opera.
The title, Così fan tutte, literally means "Thus do all [women]" but it is often translated as "Women are like that". The words are sung by the three men in Act II, Scene xiii, just before the finale. Da Ponte had used the line "Così fan tutte le belle" earlier in Le nozze di Figaro (in Act I, Scene vii).