physical and psychological safety, supportive relationships, and positive social norms (National Research Council and Institute of Medicine, 2002). However, the committee notes the review’s caveat that additional research is needed to more firmly establish whether these features of positive developmental settings “are the most important features of community programs for youth” (National Research Council and Institute of Medicine, 2002, p. 13).

Arnett (2000) describes the period of the late teens and early 20s as a distinct developmental period in industrialized societies, which he refers to as “emerging adulthood.”² In these societies, a major demographic shift toward later marriage and parenthood is leaving young adulthood as an age of great variability and exploration in all aspects of life, including where people live, go to school, and work. The developmental tasks of this period are to explore identity in love, work, and world view (e.g., values); to obtain a broad range of life experiences; and to move toward making commitments around which to structure adult life (Arnett, 2000). This work on early adult development continues the tradition of others (e.g., Erikson, 1968; Levinson, 1978) and illustrates the important influence on developmental tasks of modern economic and social conditions in industrialized societies.

Preventive interventions for young people are intended to avert mental, emotional, and behavioral problems throughout the life span. These interventions must be shaped by developmental and contextual considerations, many of which change as children progress from infancy into young adulthood. To develop effective interventions, it is essential to understand both how developmental and contextual factors at younger ages influence outcomes at older ages and how to influence those factors. The concept of risk and protective factors is central to framing and interpreting the research needed to develop and evaluate interventions.

Kraemer, Kazdin, and colleagues (1997) define a risk factor as a measurable characteristic of a subject that precedes and is associated with an outcome. Risk factors can occur at multiple levels, including biological, psychological, family, community, and cultural levels. They differentiate