Aggressive behaviors could be considered as a dynamic of communication, in which aggression is a language to be understood, to be deciphered by two protagonists : the aggressor coping with a stressful and threatening situation and the aggressed individual coping with an aggressive acting out. The following questions are addressed: (a) What does aggression mean to the aggressor, what does it mean to the aggressed individual? (b) What does the aggressor want or try to express, and why does he or she use this mode of expression and action over another? (c) How does the aggressed individual react, and what is the impact of his or her response on the aggressor? This article reviews studies on the definition of aggression, its measurement, its developmental role and its associated risk factors in children and adolescents. First, aggression in children and adolescents with typical and atypical development is examined based on a developmental approach, clinical case studies in child and adolescent psychiatry, and an empirical study on aggression in autism. Then, in light of these studies, the problem of violence among younger and younger children and adolescents, is discussed. Finally, taking together these studies and discussion, a model is proposed that accounts for factors involved in aggressive behaviors and for different possible levels of intervention. Physical and/or psychic threats generate stress and may therefore lead to offensive or defensive aggression. Stress has to be considered in its physiological dimension (biological stress responses) and psychological dimension (perceived stress). This model reveals a vicious circle: when the main response to aggression is repression, it may reinforce physical/psychic threats and stress perceived by the aggressor, and in turn aggressive behaviors. Intervention can occur at three levels: the stressful situation, the aggressor (perception of the stressful situation and his or her response), and the aggressed individual (perception of the aggression and his or her response). This model, like all models, is limited but it offers a discussion and perspectives to understand the different links that form the "chain of aggressive behavior" and the relationships between exposure to violence and expression of violence. The article concludes on the interest of a muldisciplinary approach to aggression integrating physiological, psychological and sociological dimensions.(c) 2022 L'Encephale, Paris,
