Résumé : Fertility in Sub-Saharan Africa is the highest in the world and it should continue boosting population growth for decades to come. In this paper,we showcase a new driver of fertility decisions that has been largely overlooked by demographers and economists: inheritance rules. In particular,we demonstrate that impartible inheritance (i.e. transmission of the deceased's property to a single heir) does not incentivize households to limittheir number of children. Our main empirical strategy links data from the past on deep-rooted inheritance customs for more than 800 ethnic groupswith modern demographic surveys covering 24 countries in Sub-Saharan Africa. Our spatial Regression Discontinuity Design exploiting ancestralborders reveals that belonging to an ethnic group with impartible inheritance customs increases fertility by 0.85 children per woman. We alsoestablish, both theoretically and empirically, that the fertility differences across inheritance rules are larger in lands that are less labor intensive.