Lists of rents are extremely important sources for the study of rural lordship during the high Middle Ages. Therefore, this essay examines an inventory which was issued in the Vallombrosan monastery of S. Michele in Passignano during the last quarter of the 12th century. Its aim is to combine palaeographic and historical observations, in order to provide a proper understanding of the duties with which some dependent peasants had to comply, with specific regard to labour-services (operae). Moreover, such a method makes it possible to reflect on the differences between the content of rentals on the one hand, and of lease charters on the other. In its turn, this improves our knowledge of forms of land management around the abbey of S. Michele in the examined period.