The letters of Francesco Bruni, secretary to three popes, which are printed in the appendix to this article, belong to a largely unexplored collection in the State Archives of Florence, the Carte Del Bene. This important family archive contains business records and private papers of the Del Bene family, a small but prominent mercantile house in Trecento Florence. While the account books are of primary interest to the economic historian, the letters contain valuable information on political and social problems and, in the case of these letters, on aspects of ecclesiastical history. Francesco Bruni was a close friend of the Del Bene, and to this connection we owe the fortunate survival of six of his letters from the papal curia. The sources on the Avignonese papacy are many and varied, but this epistolary collection throws light upon certain features of the curial administration and its personalities which are not well documented by other types of evidence.