This article examines the activities of militants advocating the introduction of pronatalist and pro-family education in French schools and army barracks between 1920 and 1940. After the First World War, the main pronatalist association, the Alliance nationale pour l’accroissement de la population française (National Alliance for the Growth of the French Population), undertook to raise awareness among children and young adults about the decline in the birth rate. We examine under what conditions this teaching was initiated, the means used to disseminate the information produced and the consequences of its introduction. We show that this teaching made it possible to introduce population issues and the techniques and tools of demographic analysis into schools. The pronatalist activists thus contributed to the establishment of “literacy in demography”, though their objective was to educate individuals rather than to initiate them to demography and population issues.