Besides seeking to outline social changes over two centuries in a medium-sized Italian town very different from the greater centres of Northern and Central Italy, this study aims chiefly at defining the concept of nobility as it appeared at Perugia, tracing changes in its meaning and investigating its relationship to knighthood, so important a feature in the definition of nobility in areas of Northern Europe, and to the Italian anti-magnate legislation. Attention has thus been directed towards the changing patterns in social vocabulary of honour and distinction as well as to a prosopographical analysis of those families who, by 1333, were classified as noble in the Perugian magnate lists. Their overwhelmingly rural base has been noted. The ancient territorial aristocracy continued both independent and strong, although newer families had emerged c.1200 upon old lay and ecclesiastical lands. Perugian political history has been re-evaluated; special consideration has been given to the actual powers of the 'popolo' during the period of its apparent predominance, c.1260-1400, to the complex interaction between town and countryside, to the persistence of private jurisdictions and to the degree to which the rural nobility was attracted to urban life. Finally, from 1370, the gradual assimilation of members of the mercantile classes to the ranks of the nobility has been traced, together with the formation of an urban oligarchy. In this way, both noble and civic consciousness in Perugia at the close of the Middle Ages were considerably modified.