Numerous statistical studies show that growing up in a large family has a negative impact on a child''s academic future. A survey, which involved around 20 families being interviewed, showed, to the contrary, that siblings can be a resource, in particular in those families with very little cultural capital. The article analyses the methods and effects of cultural and educational support given by older siblings in large families. While, in certain circumstances, older siblings can have a beneficial impact on the academic progress of younger siblings, we can also observe a parallel positive influence on the academic career of older siblings and on parenting practices.De nombreuses enquêtes statistiques montrent que le fait de grandir au sein...