Prevention Science and Positive Youth Development
In the 1970s and early 1980s, most prevention programs limited their focus to individual level risk or protective factors, and generally addressed only one or two predictors. Tolan & Guerra, (1994: 10), in their review of violence prevention programs, found that: "Most interventions tend to focus on changing one promising risk factor, and most emphasize changing only individual (and not social or environmental) characteristics." In reviewing pregnancy prevention programs, Kirby (1997) reported similar findings.
Yet, longitudinal studies conducted over the past 30 years identified many factors in neighborhoods, families, schools, and peer groups as well as within the individual (Brewer, Hawkins, Catalano & Neckerman, 1995; Coie, et al., 1993; Dryfoos, 1990; Hawkins, Catalano & Miller, 1992; Farrington, 1996; Loeber, 1990) that predicted problem behaviors. Exposure to increasing numbers of risk factors was found to increase the likelihood of a child's problem behaviors, while exposure to increasing numbers of protective factors was found to prevent problem behaviors in spite of risk exposure (Hawkins, Catalano & Miller, 1992; IOM, 1994; Newcomb, Maddahian, Skager & Bentler, 1987; Pollard, Hawkins, & Arthur, 1998; Rutter 1987a,b; Sameroff & Seifer, 1990).
Moreover, research showed that many of the same risk and protective factors predict diverse adolescent problems, including substance abuse, delinquency, violence, teenage pregnancy and school dropout (Dryfoos, 1990; Hawkins, Jenson, Catalano & Lishner, 1988; Howell, Krisberg, Hawkins & Wilson, 1995; IOM, 1994; Loeber, StouthamerLoeber, Van Kammen & Farrington, 1991; Slavin, 1991), that problem behaviors are correlated with one another (Elliott, Huizinga & Menard, 1989; Jessor & Jessor, 1977; Zabin, Hardy, Smith & Hirsch, 1986), and typically cluster within the same individuals and reinforce each other (Benson, 1990; Dryfoos, 1990; Jessor, Donovan & Costa, 1991). These findings suggested the need for more comprehensive or "non-categorical" approaches for preventing a broad range of youth problems (e.g., Catalano & Hawkins, 1996; Dryfoos, 1996, 1994, 1990; Hawkins, Catalano & Miller, 1992; Kirby, 1997; Moore, Sugland, Blumenthal, Glei & Snyder, 1995; Perry, Kelder & Komro, 1993; The National Academy of Sciences, National Research Council, 1996, 1993; Weissberg & Greenberg, 1997). Like youth development practitioners, prevention scientists became increasingly dissatisfied with a single-problem approach to prevention.
Prevention research also showed that different risk and protective factors are salient at different stages of a child's development (Bell, 1986). For example, while aggressive behavior from the early elementary grades appears to be a stable predictor of teenage drug abuse, poor achievement stabilizes as a predictor of drug abuse only in later elementary grades (Kellam & Brown, 1982). Prevention scientists began to emphasize the importance of attending to developmental theory and research in designing prevention programs. Information on developmentally and environmentally relevant task demands (Kellam & Rebok, 1992), as well as on specific developmental processes (Catalano & Hawkins, 1996) was incorporated to make preventive interventions appropriate to the youth's developmental stage and challenges.
There is a growing emphasis on the integration of developmental theory with models from public health, epidemiology, social work, sociology and developmental psychopathology in conceptualizing, designing and implementing preventive interventions (Cichetti & Cohen, 1995; Cichetti, 1984; Kellam & Rebok, 1992; Lorion, 1990; Sameroff, 1990; Sroufe & Rutter, 1984). As concepts in development have broadened to include ecological analysis (Belsky, 1993; Bronfenbrenner, 1979, 1995; Garbarino, 1992) and multivariate examination of causation and risk (IOM, 1994; Rutter, 1987a & b), developmental theory has become more able to provide a powerful framework for organizing and building the field (Weissberg & Greenberg, 1997: 9).
All these developments led prevention scientists to call for a broader focus in preventive interventions: the identification of important connections between risk and protective factors and youth outcomes; the evidence that problem behaviors share many common antecedents; the evidence that the number of risk and protective factors to which a youth is exposed strongly affects that youth's likely outcomes; the importance of factoring age-appropriate task demands and processes into prevention program design; and documentation that early initiation of problem behavior is itself a predictor of poor outcomes.