very limited (Collins et al., 2000). Scientists have mapped the human genome, but they know little about how it influences the development of individual differences. Research suggests that the processes may be complex: development always occurs in interaction with environments; certain environments may be more likely to bring out specific traits; genes may partly shape development by influencing the choices children make regarding the environments in which they spend time. Given the lack of knowledge, extreme caution is required in applying the ideas of behavioral genetics to real-life situations. Nonetheless, it is important to realize, as any parent with two or more children knows, that individuals are not infinitely malleable; some (and only some!) of the emotional and cognitive dispositions that they bring into a community program may not be substantially alterable, even with the greatest staff in the world.
This fact and the other theories covered above lead to another important psychological perspective concerned with person-environment fit. If individuals are not infinitely malleable, then the design of optimal learning environments requires that environments be adaptable to individuals, or it requires that individuals be selectively placed into environments that suit their dispositions. Piaget’s (1971) and especially Vygotsky’s (1978) theories also suggest that youth learn best in environments that provide information and support at a level that is at or somewhat above their current level of cognitive development (in what Vygotsky calls the “zone of proximal development”). These issues of person-environment fit appear to be particularly salient in early adolescence, when young people’s abilities and needs are changing rapidly. Eccles et al. (1993) show that junior high schools often fail to provide this fit to the developmental stage of young adolescents, resulting in diminished levels of interest, motivation, and learning among junior high students. They theorize that a similar lack of developmental fit often occurs in the family, accounting for the increased rates of conflict that many young adolescents experience with their parents. The message of this theory, indeed of psychological theories in general, is that positive development is most likely to occur in environments that are attentive to and matched with the dispositions and developmental level of the individual. To engage an adolescent in growth, one must engage that human being in an environment that makes sense to her or him.
In addition, to be successful programs must be developmentally appropriate and must have a developmental agenda. That is, they need to have provisions for the participants to grow and take on new roles as they mature as program members. The activities also need to relate to