The thesis aims to analyse Leonardo Sciascia's non-fiction prose through the methods of stylistic criticism and text linguistics. Sciascia is the author of a diversified production of fictional, critical and journalistic prose. His sophisticated use of language is at the service of an original and penetrating interpretation of the political and social events of 20th century Italian history. A restricted corpus of nonfictional works was taken into consideration in order to closely examine the main rhetorical and argumentative procedures, the techniques of assembling syntax and discourse, lexical and expressive choices. Here are the texts examined: La corda pazza (1970), La scomparsa di Majorana (1975), L’affaire Moro (1978), Nero su nero (1979), Il teatro della memoria (1981), Dalle parti degli infedeli (1981), Cruciverba (1983), La strega e il capitano (1986), A futura memoria (1989), 1912+1 (1987), Fatti diversi di storia letteraria e civile (1989).