This chapter reviews the evidence for the archaeology of early Christianity in Britain and Ireland. Here, the church had its origins in the areas that lay within the Roman Empire in the fourth century but rapidly expanded north and west in the early fifth century following the end of Roman rule. The evidence for church structures is limited and often ambiguous, with securely identifiable sites not appearing to any extent until the seventh century. There is a range of material culture that can be linked to the early church from the fourth to the seventh centuries; in particular, there are strong traditions of epigraphy and increasingly decorative stone carving from most areas. The conversion to Christianity also impacted burial rites, although the relationship between belief and mortuary traditions is not a simple one.