The under-representation of women in criminal statistics has seldom been studied by sociologists. Yet, it masks the gendered nature of normative systems. In this regard, prisons offer a perfect field of study, provided they are not considered as autonomous institutions distinct from the broader social universe, but rather as a magnifying glass which informs us about the screening operated by the criminal channels and, more generally, about social relations. As single-sex spaces, they clearly highlight the relationship between social order and gendered order, and allow us to grasp the gendered norms which preside over the construction of feminine deviance beyond the penitentiary system.