A delinquent behaviour can be determined by the circumstances with personal, subjective nature (offender’s personality) or social, objective concern (actual conditions of the crime). Between these two aspects of the aetiology of juvenile delinquency there is interdependence, because the personality of a young offender is a set of bio- psychosocial factors. So, his identity is due to the specific psychophysiological features and the influences from its social environment, significances that are assimilated and integrated into the internal structure of the minor’s personality.