This study examined the predictive validity of preadolescent Type A determinants for Type A dimensions in young adulthood (n = 375). Predictive variables, i.e. hyperactivity, aggression, social maladjustment and self-esteem were measured when the subjects were aged 12. Type A dimensions, i.e. hard-driving, competitiveness plus aggression and impatience were measured in the same subjects when they were aged 18. "Impatience" was predicted by means of preadolescent hyperactivity, and "competitiveness-aggression" by social maladjustment. "Hard-driving", which was most strongly related to CHD risk factor levels in young adulthood, was anteceded by the subject's feeling that he or she could not cope with life. This supports the hypothesis that Type A behaviour is a coping mechanism: a person tries to cope with stress by increasing his or her level of achievement.