criminal opportunity by focusing on involvement in relationships or exposure to situations that promote crime example, Bratt 12003) compared cannabis and alcohol use in a group of Norwegian teenagers before and after social workers were introduced to The settings where youth gathered outside of homes. The guardians did not have a" substantial preventive effect on use of alcohol and may even have contributed increased use of cannabis He concluded that participation in unsupervised activities is not a sufficient cause of delinquent behavior, but it is a necessary cause.