This is the first full-length study of Scottish royal government in the twelfth and thirteenth centuries ever to have been written. It uses the untapped legal evidence to set out a new narrative of governmental development. For the first half of the twelfth century, kings ruled primarily through personal relationships and patronage but through administrative and judicial officers only in the south of their kingdom. In the second half of the twelfth century, these officers spread north yet it was only in the late twelfth century that kings routinely ruled through institutions, and, even as they developed over the thirteenth century, kings continued to rely on aristocratic power as an increasingly formal part of royal government. The book refines and overturns previous understandings in Scottish historiography of subjects as diverse as the development of the Scottish common law, Anglo-Norman feudalism, and the importance of the reign of David I. In addition, it argues that Scottish royal government was not a miniature version of English; there were profound differences between the two polities arising from the different role and function aristocratic power played in each kingdom. The formalization of aristocratic power within and alongside the institutions of royal government in Scotland forces us to question whether the rise of institutional royal power necessarily means the consequent decline of aristocratic power in medieval polities. The book explains an important period in the history of Scotland, and places the experience of Scotland at the heart of the process of European state formation.