providing opportunity for repetition (of routines, stories, and activities that promote social and cognitive skill development) and practice of valued skills, the brain becomes more efficient in those areas, freeing attention for higher-order thinking.

Early childhood is a period of tremendous cognitive, social, and emotional growth. While there do appear to be systemic stages of development that place a ceiling on what a child can do or learn, beneath that ceiling there is significant variation among children, and across domains in a given child. The window into the developing brain allows us to see that stimulation from the environment changes the very physiology of the brain, with implications for cognitive, social, and emotional growth.

The ability of the environment to substantially alter developmental outcomes in the early years suggests the potential for preschool programs to have a powerful impact on child development. But a large research base supports the notion that if that impact is to be positive, preschool programs must attend to cognitive, social, and emotional development simultaneously. We addressed the importance of children’s early relationships with adults, emphasizing that emotionally secure relationships are crucial in early education and care settings and are predictive of children’s social relations with peers, their manifestation of behavior problems, and school achievement when they are older.

The thrust of the research reviewed above suggests that development is not simply an unfolding of innate capacity, but varies with context. It is a dance in which nature—what the child brings into the world—and nurture—the relationships and other aspects of the child’s context—are partnered. Because nature and nurture are unique for every child, we observe remarkable variation among children even at very early ages. The research reviewed above suggests that responsiveness of those in the nurturing role to the developmental level and characteristics of the child is key to supporting further development. We therefore turn our attention in the next chapter to some of the central aspects of variation among preschool-age children to which an attentive adult might respond.