happen at predetermined times, or is it more loosely open to environmental influences and primed to seize those that matter most whenever they occur?

• Do infants follow a smooth and predictable path toward the preschool years (and beyond) or is early growth and development characterized by bumps, detours, and unanticipated turns?

• Are infants initially incompetent, passive creatures or individuals who are born with an active capability to learn from the surrounding world?

• Are young children highly vulnerable, highly resilient, or both?

The discussion provided in this section reflects the prevailing views of researchers, theorists, and clinicians who study young children. This multidimensional knowledge base has grown exponentially over the past 25 years, fueled by an explosion of scholarly work across a wide variety of disciplines. Its richness lies in the extent to which diverse perspectives have converged on a set of core concepts. Its limitations rest on the extent to which the science is based largely on studies of typical development in white, middle-class samples and developmental vulnerability in samples that do not disentangle race, ethnicity, or socioeconomic status.

Focusing on the underlying principles that guide the developmental process, this report highlights ten guiding principles or core concepts.

1. Human development is shaped by a dynamic and continuous interaction between biology and experience. Early pioneers in the field of child study approached the complexity of human development by devising simple models and testing them. Some, such as Arnold Gesell (1925, 1929), believed that the emergence of skills is driven primarily by genes. Others, such as John B. Watson (1928), believed that all behaviors are determined by the environment. These early models reflected a mechanistic conceptualization of development that was derived from the physical sciences. Over time, it became increasingly clear that humans do not behave like machines (neither the prewired nor the programmable type), and children began to be viewed through the lens of modern biology, rather than that of classical physics or chemistry. Consequently, human development is now described in interactive terms (i.e., “dynamic”), reflecting the essential characteristic of a living organism.

Virtually all contemporary researchers agree that the development of children is a highly complex process that is influenced by the interplay of nature and nurture. The influence of nurture consists of the multiple nested contexts in which children are reared, which include their home, extended family, child care settings, community, and society, each of which is embedded in the values, beliefs, and practices of a given culture. The influence of