Much work has already been done on the conventions and formulae of Old French literature, particularly epic literature, and on parody in the French Middle Ages. This book links these approaches, widens the concept of 'formula', and aims to show that certain authors, far from being enslaved by the conventions within which they worked, were conscious of them and could master them with sufficient independence to exploit them for calculated literary effect, and in particular for parody. It studies the fabliaux, Aucassin et Nicolette and Le Pèlerinage de Charlemagne, texts in which formulae play a varied and subtle part. In the fabliaux we find that formulae borrowed from serious literature add parodic depth to the often simple humour of these tales, but that the genre as a whole is not essentially parodic. Aucassin et Nicolette uses conventions to arouse expectations which may or may not be satisfied; parody proves to be fundamental to this work. The approach shows its full potential when applied to Le Pèlerinage de Charlemagne; study of this text's use of formulae of the epic and romance traditions reveals a high degree of complexity and a finely nuanced parody.