Infancy is a unique period, in that at no other state is there greater growth and development. During this time, growth is occurring at a physical level, but equally impressive are the socio-emotional and cognitive developments during this time. Genetics, the womb environment, and the physical environment after birth all combine to impact the rate and manner of growth. Who we ultimately become as individuals begins here. Intended for university and public libraries, the Encyclopedia of Infant and Early Childhood Development is the major reference work that provides a comprehensive entry point into all of the existing literature on child development from the fields of psychology, genetics, neuroscience, and sociology. The scope of this work is to understand the developmental changes, when they occur, why they occur, how they occur, and those factors that influence that development. Although some medical information is included, the emphasis is on normal growth and is primarily from a psychological perspective.