The aim of this thesis is to discover how parishes evolved in North-east Yorkshire. It seeks the origin of the parish system in the 7(^th) century with the establishment of monasteria in accordance with the theory, the 'minster' hypothesis, that these were the ministers of the Middle Ages and the ancient parish churches of today. The territory of the monasterium, its parochia, was that of the secular royal vill, because kings granted these lands with the intention that monasteries provided pastoral care to the royal vill. The parochia fragmented in later centuries into parishes through the building of private or proprietary churches or Eigenkirchen. This thesis, therefore, looks for answers to three main questions (i) were monasteria centres of pastoral care and performing the function of later parochial churches, (ii) were the territories of monasteria coterminous with the secular land units, and can these be recreated using later manorial boundaries, and (ill) were these monasteria superior mother churches during the Middle Ages and distinct from other churches in the area? The study area comprises the monasteria of Whitby, Hackness and Lastingham, and compares these to the non-monastic site of Pickering, which may have been the site of a secular 'minster'. It was concluded that there is no evidence that the monasteria provided pastoral care as part of their function and that their parochiae cannot be recreated using later manorial boundaries, i.e. those from Domesday Book. They were not superior churches in the later Middle Ages. However, Pickering was a superior church but the extent of its early medieval territory cannot be recreated from Domesday Book. An alternative view regarding the development of parishes in the area was proposed, which suggested that the bishop, influenced by the church benefactor, based the parish boundaries around township boundaries