Dario Fo needs no introduction, though he is less well known for his work as a critical theorist of theatre than in his role as a playwright. The original Theatre Quarterly was the first journal to publish his critical writing in English, and two of his more recent essays-‘Theatre of Situation’ and ‘Retrieving the Past. Exposing the Present’ - appeared in one of the earliest issues of New Theatre Quarterly. NTQ2 (1985). Here, we are pleased to publish Fo's brief but stimulating study of the conventions and the ‘language’ of theatrical masks, in which he outlines typologies stretching from Ancient Greece to commedia and beyond, and suggests some of the distinctive requirements for the contemporary actor of performing in mask. The translation is by Gail Macdonald.