'Difficult adolescent' is a clinical category defined by psychiatrists' expertise. Since the end of the 1990s, it has been extensively used to describe a population of disruptive, violent yet vulnerable adolescents, at the margins of public institutions that manage youth deviancy in France. For the present study, an interconnected network of 49 documents was analysed using a genealogical method in order to provide comprehensive elements in the results. This category found its ecological niche in the 1960s, revealing a moral tension in the use of constraint. It addressed new problems of intractable individuals, whose dangerousness and vulnerability require coordination between penal, social and psychiatric institutions. It defines an ambiguous condition, suspended between the trouble experienced by the caregivers and an adolescent's individual disorder.