This thesis aims to explore the human-dog relationship in early medieval England and Ireland (c. AD 400-1250) and so develop an improved understanding of how people perceived and utilised their dogs. In 1974, Ralph Harcourt published a seminal paper reviewing the metrical data for archaeological dog remains excavated from British antiquity. Nearly forty years on, many more dog bones have been excavated and recorded. His results from the Anglo-Saxon period illustrated that the degree of skeletal variability had reduced after the end of the Roman occupation, with an increase in the average size. He also observed two distinct groups in the estimated shoulder height measurements. The key areas that have been considered include: dog functionality, morphology, and treatment. Influences that may have led to changes in people’s perception of dogs during this time period have been examined. Differences between England and Ireland are assessed, but variation in recording methods has meant the data obtained on the Irish dogs were limited. An interdisciplinary approach has been taken, combining archaeological, historical and anthrozoological information. New evidence has shown that humans’ relationships with dogs were more complex and varied than previous research would suggest, especially in the treatment of dogs at their death. This was particularly evident in England, where a change in the burial location of dogs was observed from the end of the seventh century, and could be linked to the development of Christianity and its negative teachings towards the dog. More metrical data from English sites have shown that the two distinct groups observed in Harcourt’s Anglo- Saxon results were no longer apparent.