In this article based on the analysis of several corpuses of medical and administrative reports, the discourses produced on the age of puberty of girls before and after the French Revolution are explored. The representations have changed: the abnormality of late menstruation in the countryside makes way for the criticism of precocity. The answers on the tendency in age at puberty (permanence or decline) are diverse and emphasis is given to the role of “moral” causes, in the context of populationism, to the detriment of factors like nutrition or physical work.