Alsace was a contested region in the early Middle Ages, and struggles for its control by rulers of east and west Francia, Burgundy and Lotharingia generated a relatively substantial amount of source material. Hans Hummer's clear and scholarly analysis of this material – centred on the large body of charters from the monastery of Weissenburg – not only establishes him as a worthy successor to the great historians of the region such as Heinrich Büttner, but also continues a series of recent studies that have demonstrated the great potential of a regional focus for providing insights into the entire Frankish political and social order. Hummer argues that monastic houses were the defining institutions of this order. The Carolingian rulers tapped into the growing social importance of monasteries by regularising precarial land grants (by which patrons gave land to a church and received it back conditionally in return for a regular payment) and claiming the right to redistribute some types of monastic land for their own purposes. This contributed to the intensification of royal government in areas like Alsace, particularly evident during the reign of Charlemagne, and encouraged an increasing social and political hierarchisation. By the high Carolingian period of the ninth century, when Alsace's geographical position made it an object of intense competition between rulers, the area's major abbeys acted as focal points for the identity of their patrons and from this perspective Hummer argues that the cartulary of Weissenburg (c. 860) was a collaborative venture between its monks and benefactors. The landed resources and institutional memory of such monasteries meant that they were able to support long-lasting family identities and claims to property over many generations. The resultant social order remained relatively stable until the tenth century when, Hummer argues, the alliance between ideologically dedicated monastic reformers and powerful Ottonian kings helped to weaken aristocratic control of churches, causing lords to shift the seats of their power to upland fortresses and instigating a decisive shift in one of the fundamental social institutions of the previous centuries. All this is argued with great verve, economy and scholarship, and along the way the reader is treated to original takes on many aspects of contemporary politics and culture – among the book's virtues is its emphasis on lordship during the Carolingian period, which is a subject in need of more attention. Inevitably, questions about the typicality of Alsace pose themselves. Does the unusually high proportion of precarial charters in the Weissenburg cartulary mean we run the risk of overestimating the importance of monastic foundations to the power of eighth- and ninth-century lords (as opposed to other factors such as office-holding or arbitrary violence)? The degree to which monastic reform had an impact on lordship in the tenth century might be queried on the same grounds; and also because the argument rests primarily on the highly-charged rhetoric of hagiographers whose loud proclamation of a separation between lay lords and monasteries inevitably looks different from the picture of collaboration drawn from ninth-century (and indeed tenth-century) charters. This is an excellent book that poses new questions as well as looking afresh at some old ones.