At the end of the thirteenth century, the commune of Florence placed a group of noble families under a set of legal restrictions, on the grounds that they were both the most powerful and the most violent and disruptive element in the city. These nobles, termed magnates, were barred from most political offices and required to post security for good behavior. The ordinances were imposed by a new guild-based government, which sought to stabilize Florence after decades of factional war. Interpretation of this conflict has been a central problem in Florentine history, with debate focussed on whether the statutes represented the victory of urban consumers over rural producers, or simply a minor political turnover in a homogeneous ruling class. The dissertation, based on research in the notarial collections of the Florentine state archives, offers a broader view of the families restricted under the statutes as urban magnates. These families were the heirs of a twelfth century form of social and political organisation, in which power derived from kinship ties and alliances rather than professional associations. Noble families formed lineages, which excluded women from real membership and inheritance and brought kinsmen into close alliance, enabling them to share resources which included urban and rural forts, l and , patronage rights, and the less tangible assets of family indentity and prestige. Ideally, a lineage lived together in a family enclave of houses and palaces, protected by towers. Through these means, powerful lineages controlled their neighborhoods and competed to dominate communal offices. The group of magnates was defined in part by past political involvement, and in part by aristocratic culture and style. The statutes against the magnates reflected the contemporary debate over the nature of the true nobility. Nobility was sometimes seen as a matter of birth and wealth, sometimes as knighthood and courtly manners. For Dante and other Florentine authors, true nobility meant interior qualities, virtue and moral capacity. Ironically, by the time the statutes were imposed, the older magnate culture was changing. Individuals gave up the most disadvantageous elements of the lineage, rejecting joint property and collective liability. Men began to turn for assistance not to their kinsmen, but to outsiders: to churchmen, to civic institutions, even to their wives and sisters.Ph.D.Medieval historyUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/160170/1/8422275.pd