This thesis analyses the political and institutional development of the populus of the Umbrian city-states in connection with the municipal documentary activity in the second half of the thirteenth century. The aim of the research was to identify the initiatives explicitly promoted by the populus in the field of production and documentation management. Umbria was chosen as field of study because of its historical and geographical context, characterized by a particularly high density of small and medium city-states and a remarkably rich municipal documentation. This research has focused in particular on the city-states of Assisi, Gubbio, Orvieto, Perugia, Spoleto and Todi, all presenting different characteristics, such as territorial extension, incisiveness of popular regimes, relevance in historiography field. In this area municipal records directly related to an offitium of the populus’ institutional bodies have been identified and analysed. The gradual affirmation of the populus in the Umbrian city-states government as well as the many documentary initiatives specifically commissioned by popular magistrates are characterized by the extreme variety of the solutions adopted both in the institutional field and in the municipal documentation management. Finally re-writing of certain acts, operated by the offitium capitanei populi, seems to indicate a direct interference and a control of the capitaneus in preforming certain tasks by other municipal offitiales.