Charters reveal the important role mothers played in introducing their sons to routine actions of rulership and lordship in the eleventh and twelfth centuries. Yet modern scholarship has overlooked this collaborative, maternal aspect of a child’s preparation for rule. This article uses royal and aristocratic case studies from across north-western Europe to show mothers’ active participation in their sons’ political education. An examination of the language and imagery of medieval charters – with a focus on graphic features and methods of authentication – reveals the consistency of the mother-son partnership despite variations in regional diplomatic practices. A comparative perspective also allows further insight into how administrative changes across the twelfth century eradicated the very aspects of medieval diplomatic in which mothers had previously featured so prominently with their sons. This article complements and challenges prevalent legal and constitutional perspectives by placing motherhood and childhood at the forefront of an analysis of practices of association, political education and rulership. It demonstrates the central role women played in acquainting their sons with the networks, strategies and actions of rule.