The UNDERISK research trajectory is closely linked to the study of risk factors for antisocial behaviour and delinquency. To this end, several research projects and studies were aimed at evaluating those factors which might influence the appearance and maintenance of these behavioural typologies, mainly from a longitudinal methodology. The most relevant risk factors include those related to parenting practices, temperamental and personality characteristics, or different psychosocial factors associated with the school environment or association with the peer group.