This is a survey of the religious attitudes reflected in Latin literature from the late Republic to the time of Constantine. Its main theme is the development of the Roman public religion in that period. Within this theme the most pervasive issue is the relationship between Roman religion and morality. Though the link between the two is shown to be closer than is often supposed, it was also the case that the rise of such systems as Stoicism and Christianity contributed to a sense of morality more detached from traditional conceptions of the collective well-being of the Roman state. Nevertheless, the old religion continued to flourish and to contribute in numerous ways to the working of Roman society until it was fatally weakened by the political and social crisis of the third century. This crisis, and the tendency of the Roman Empire to depend upon and encourage new sources of support, prepared the way for the emergence of Christianity, first as the religion of the Emperor, and then, after a period in which Christians and pagans were able to co-operate by emphasizing their common beliefs, as the official religion of the Empire.