This volume adopts a unique, multidisciplinary approach to the study of the development of the human brain and early behavior. It includes chapters by researchers from several disciplines whose work addresses specific aspects of brain-behavioral interactions in development. The chapters provide strong evidence that the development of both brain and behavior is a response to biological and environmental variations. Language is also discussed, and provides a useful example of biosocial development because linguistic and brain functions and development can be examined under controlled conditions of both genetic and environmental deprivation. Research in this area has produced particularly exciting results pointing to the universality of language capacity among humans and illuminating the processes by which language competence develops. Brain Maturation and Cognitive Development provides new views in the understanding of human nature and present new, biosocially oriented research directions that are unique in their focus.