The letters of Anselm of Canterbury (a 1109) provide the clearest insight into his mind and action, and they also constitute one of our finest vantage points to observe the formation of those profound forces moulding Europe in the late eleventh- and early twelfth centuries. The focus of the present study is the transmission of Anselm’s correspondence. It argues that many of the conclusions of earlier scholarship have been constructed on flawed foundations. Using evidence from all known manuscripts and printed editions, the study seeks to demonstrate precisely how Anselm’s letters have survived and how the surviving witnesses relate to one another. The study also aims to define the historical contexts within which our key manuscripts were copied and edited. Only when equipped with this store of information can we begin to understand the editorial processes that shaped the textual tradition of Anselm’s letter collections before and after his death.