The article aims to highlight and analyze the sources relevant to the reconstruction of social mobility in Southern Piedmont during the 16th and 17th centuries, with specific reference to the Tortona area, which belonged to the Duchy of Milan in the period considered. The sources preserved in the archives of the municipalities of Tortona and Castelnuovo Scrivia are presented and described, highlighting the limitations and opportunities offered by this type of documentation in order to monitor the evolution of family assets during that period. These reflections are connected to the socio-institutional context at both local and regional levels. Finally, an analysis of these sources is carried out to study social mobility in Castelnuovo Scrivia for a few decades of the 17th century.