When considering aggressiveness and violence during adolescence, we must take into account multiple senses, which range from the healthy assertion of one's own space before others to the repetition of traumatic violent experiences such as the violation of bodily and spatial-temporal boundaries. The author presents a survey of the views of different authors within psychoanalytical literature which allows us to question these terms, and turn then to the exploration of clinical practice. In studying the latter, acting out is brought to the fore, noting that not every adolescent act connotes a risk. The acts tackled in this case are those that, owing to their characteristics, may often endanger the very life of the adolescent. The author presents clinical material that focuses on adolescent acting out, highlighting the question of how to create, through the transference-countertransference axis, a space within the analytic session where the patient's capacity to think may be incorporated, thus allowing the anticipation of action.