This thesis deals with one aspect of religious intolerance in the later Roman empire, that which was expressed by the Imperial government during the fourth century from the reign of Constantine to the death of Theodosius I. As such, all the sources used are Imperial letters and laws which have survived in the Theodosian and Justinianic Codes as well as other Imperial statements that have survived in other collections, such as that of Eusebius’ Vita Con stan tin i. The thesis attempts to gauge the amount of religious intolerance exhibited by each emperor in this period through an analysis of their laws and letters that were concerned with religious affairs. As such it is divided into four chapters: the first covers statements issued by Constantine and his immediate successors; the second focuses on Constantine’s involvement with the Donatist dispute of north Africa; the third examines the meagre record from Jovian’s short reign, before concentrating on the Valentiniani and the fourth and final chapter analyses Theodosius' religious legislation. The analysis of laws and letters in each chapter is divided into sections that essentially follow the structure of the Theodosian Code itself; i.e. the first section will cover an individual emperor’s laws on the Church and Christianity, followed by his laws on heretics, followed by those on Judaism and finally those on paganism. Whenever possible, the thesis attempts to seek some explanation for the laws issued, especially those that appear to be most intolerant. This is achieved through examination of political or other factors that may have been motivating factors behind the issuance of each law. Sometimes the individual suggeren s and addressee are demonstrated to have influenced the nature and character of each law. As such, the style of the thesis takes the form of a historical and social commentary of the laws issued. Throughout the thesis the argument is advanced that the Christian emperors and their administration were not necessarily as intolerant as ostensibly appears to have been the case and that as such, there is little evidence that the Christian state was, thereby, intolerant.