This second volume in the History of Mediaeval Canon Law series discusses the earliest papal decretals, covering the period from the end of the 4th century to the end of the 9th century. In contrast to earlier scholarly works, which usually skim over the beginnings of the papal decretal tradition and the earliest collections containing them, the authors begin with the first papal letters and thoroughly describe their transmission and reception into the canonical tradition up to Gratian's "Decretum" (1140). They examine the letters of 25 popes from Siricius (384-399), whose pontificate undoubtedly produced the first known papal decretal in 385, to Stephen V (885-891).