This sourcebook gathers into a single collection the writings that illuminate one of the most fundamental periods in the history of Christian Europe. Beginning from the Great Persecution of Diocletian and the conversion of Constantine the first Christian Roman emperor, the volume explores Christianity’s rise as the dominant religion of the Later Roman empire and how the Church survived the decline and fall of Roman power in the west and converted the Germanic tribes who swept into the western empire. These years of crisis and transformation inspired generations of great writers, among them Eusebius of Caesarea, Ammianus Marcellinus, Julian ‘the Apostate’, Ambrose of Milan, John Chrysostom, Jerome and Augustine of Hippo. They were also years which saw Christianity face huge challenges on many crucial questions, from the evolution of Christian doctrine and the rise of asceticism to the place of women in the early Church and the emerging relationship between Church and state. All these themes will be made accessible to specialists and general readers alike, and the sourcebook will be invaluable for students and teachers of courses in history and church history, the world of late antiquity, and religious studies.