This research must not only identify 'high risk' characteristics, but should also investigate why certain characteristics entail high risk. Knowing the characteristics that put children at high risk is important in identifying a target population for prevention efforts. In deciding which prevention efforts are likely to be effective, it is useful to understand why these characteristics relate to later delinquency. This research review found that early aggressiveness and/or antisocial behavior were shown to be important antecedents to later delinquency and criminality, and high research priority should be placed on examining the origins and ways of reducing levels of early aggressiveness. Moreover, prevention research should simultaneously examine other adolescent outcomes, so that specificity of antecedents to one or several outcomes can be determined. Finally, longitudinal studies should be used to test the effects of normal events, such as school success or failure, (in addition to the evaluation of prevention and intervention efforts) on future delinquents. 33 references.