shown that economic hardship is associated with dysfunctional families and with a range of difficulties for adolescents, including risk-taking. This sort of stress is likely to have a negative effect on parenting, yet positive parenting can also profoundly affect outcomes for young people. Adolescents also tend both to seek out peers like themselves and to become more like the peers with whom they associate—and here, too, the net effect may be positive or negative, although the precise mechanisms of these fluid relationships have not been systematically traced.

Similarly, strong bonds with teachers and peers at school can be a positive influence, but many characteristics of middle and high school are not conducive to the development of such bonds. Communities also may have structural characteristics that are supportive of positive adolescent development—such as social networks and resources for young people—but research has not yet answered specific questions about how schools and communities can develop more favorable structures and cultures. Finally, the rapidly expanding universe of media devices and venues is having a profound influence on the experience of adolescence, with effects that include evolving norms for many behaviors—and particularly a loosening of sexual attitudes and an increase in sexual activity. At the same time, the media provide a potentially powerful tool for influencing young people in a positive direction.

Interventions that address these influences may target broad populations or specific families and individuals who have shown signs of distress. Many focus on key transition points; like the presenters on specific risk behaviors, the presenters on external influences also stressed the value of targeting the youngest adolescents before problems become more firmly established.