Hospitalizing an adolescent after an acting out is frequent. The necessity to act, and the urgency of the act in adolescence has been observed as well in adolescents that have health problems as in adolescents in good health. It is not possible to separate the acts that are symptoms of a pathological organization from the acts that are an expression of a normal psychology, but there is a tendency to conceive as psychopathological that which comes into conflict with, and that which is a transgression to, the laws of the social environment, and the biological laws. It is important for the clinical physician to know the social projections on the adolescent. In certain cases, the act is a play out of the fantasy organization of the adolescent and is a reflection of the personality of the subject: in other cases the symptom-acts are a summary of a past relationship, towards which it expresses an ending or a split; the act in an adolescent is all the more a symptom that it is isolated from a relationship.