This study was generated by the writer's twenty years of responsibility for the architecture and planning of Runcorn new town in Cheshire. It draws on this experience to chart the development of Runcorn and the towns founded by Edward 1 in North Wales between 1277 and 1284. The work is written in two principal sections dealing with Runcorn and Conway respectively and concludes with a chapter drawing together those points of comparison and contrast made apparent by the main body of the work. The first section in each part examines how these new towns each formed part of a larger programme of town building designed to re-orientate regional economies in the aftermath of war. The process of planning the new towns is then discussed in the context of contemporary functional requirements and the constraints imposed by the selected sites. The origins of the settlers recruited to the new towns is analysed and a theory put forward concerning the methods whereby the medieval new towns were populated by the royal administration. The problems of land assembly are examined and the remarkably similar principles of financial compensation for acquired land that were adopted in the medieval and modern periods. The administration and internal organisation of the new towns are compared and how these related to local government which itself was reorganised contemporaneiously with the development of the new towns. The basis of the economic life of the towns is examined in the context of wider economic factors affecting the financial fortunes of medieval kings and modern democratic government. The trades and occupations of the early settlers are analysed and the relationship of the royal administration and the development corporation to the social and economic life of the new towns. Internal trade and how this was affected by external lines of communication is considered and the concluding part of each section of the work deals with the settled towns and their relationship to the regions in which they were planted.