Regarding the prevention or reduction of delinquency, peer groups 

tend not to be very effective because of the tendency for adolescents to seek autonomy by breaking rules. 

can be effective because they often play a major role in individuals' pro-social development. 

tend not to have an impact because juveniles with pre-established risk self-select into groups. 

are more effective than families and other groups because peers are more important to juveniles.