Although there are now multiple, well-tested interventions, the effect sizes for most interventions are small to modest. Similarly, though several studies have now demonstrated results with strong empirical designs and statistical techniques, meta-analyses consistently highlight the methodological weaknesses of many studies. As discussed in Chapter 10, this is not because of a lack of appropriate methodological techniques. There is a convergence among both meta-analyses and individual studies suggesting that interventions are more effective for participants with elevated risk, including for participants in many universal interventions. However, most interventions have been tested with a single cultural group, and few have been tested in community-wide interventions that reach large numbers of at-risk youth. Continued rigorous research is needed to improve the reach of current interventions and to expand interventions that are culturally relevant and responsive to community priorities (see Chapter 11).

Mass media and the Internet present a potential opportunity to reach large numbers of young people with readily disseminable interventions. Although the currently available evidence does not support particular interventions, this is an area that warrants additional research. Mass media also offers the potential to address concerns related to stigma that serve as a barrier to prevention.

Although the research base of preventive interventions has expanded significantly, there are several groups or settings that have not been represented in this expansion. With the exception of college populations, very little research has been done related to young adulthood. Adolescence is also less well represented than earlier developmental periods. In addition, there has been limited research following young people across developmental stages. Although there is converging evidence that approaches that