Over the past several decades a voluminous literature has emerged on risk and protective factors associated with specific disorders (e.g., Garber, 2006; Biglan, Brennan, et al., 2004) and on the multiple disorders and problems that are associated with exposure to specific risk and protective factors (e.g., Luthar, 2003; Cicchetti, Rappaport, et al., 2000). This literature provides the research base for the design of preventive interventions. When potentially modifiable risk and protective factors have been identified through epidemiological and developmental research, preventive approaches can be developed to change those factors to prevent the development of mental, emotional, and behavioral problems. Other risk factors can help define populations that are potential candidates for prevention, such as children exposed to divorce, poverty, bereavement, a mentally ill or substance-abusing parent, abuse, or neglect. Although interventions aimed at these children typically do not target the risk factor itself (e.g., a divorce has already occurred), they can be designed to reduce the likelihood of problem outcomes given elevated risk.

A preventive intervention trial tests whether the intervention is effective in changing the targeted risk and protective factors and whether change in these factors mediates, or accounts for, changes in the problem outcome. Because prevention is aimed at averting problems that may occur across developmental stages, a critical feature of a prevention trial is longitudinal follow-up of participants to assess the intervention’s impact on trajectories of development. A randomized preventive trial that provides evidence that an intervention has successfully changed a risk or protective factor and that the change is associated with a later change in a problem outcome is a uniquely powerful scientific tool in moving from passive correlational studies to identification of causal risk or protective factors (Rutter, Pickles, et al., 2001; Howe, Reiss, and Yuh, 2002; see also Chapter 10). Preintervention research that tests models of the pathways between risk and protective factors and the development of mental, emotional, and behavioral problems provides evidence for the theoretical models on which preventive interventions are based. Evidence from randomized prevention trials provides experimental evidence to support or counter those models (Coie, Watt, et al., 1993).

The committee examined four specific aspects of risk and protective factors, their relations to each other and to mental, emotional, and behavioral outcomes, and implications for the design and evaluation of preventive interventions (see Table 4-2).