The prevailing opinion regarding Gallo-Roman religion is that it was a fusion between the two religions. Scholars who dissent from this view can be divided into two different groups. On the one hand, scholars contend that, during a formative period of Gallo-Roman civilisation, there was a partial abandonment of the Gallic rites, that Roman religion came to be understood to be better as well as different, and that Gallo-Roman religion offered more spiritually as well as materially. On the other hand, other researchers hold that the Gallic deities continued to be worshipped, some under a Roman guise, others in their original pre-Roman form; however, they accept aniconism, atectonism and the reports that the Romans stopped human sacrifice and headhunting. This volume argues not only that the worship of Gallic deities continued, but also that Gallic religion already used man-made sanctuaries and anthropomorphic images before the Roman Conquest, that the disappearance of human sacrifice was wrongly attributed to the Romans and that the Romans never suppressed headhunting. In chapter one some conceptual problems, including those regarding terminology, presuppositions and errors are looked at. In the second chapter the archaeological and literary sources of information about Gallic religion and their reliability are examined. Using these sources, in the third chapter, Gallic deities are identified and the enigma of the pantheon set out by Caesar is decoded. In the fourth chapter the use of formal structures of worship and ritual by the Gauls is confirmed and the essential elements of such structures are analysed, with the argument being supported by a comparison of pre-Roman Celtic sanctuaries from both inside and outside the Roman Empire. In the fifth chapter the concept of sacrifice is examined from an anthropological perspective and this approach is applied to all Gallic sacrifices; the Gallic rituals of divination and circumambulation are also examined. The basis for the magico-religious significance and popularity of headhunting is established in the sixth chapter. Finally, in the seventh chapter, the Celtic belief in an Afterlife is defined and its attraction is demonstrated. In each chapter, the number of these Gallic beliefs and customs, which continued after the Roman Conquest, is examined and it is demonstrated that Gallic religion was not abandoned, that the Celtic sanctuary design was the basis for Gallo-Roman temple design and that Gallo-Roman religion continued to be Gallic as well as Roman.