Developmental psychology is the scientific study of age related behavioral changes which occur as a child grows up. This field examines change across a broad range of topics including: motor skills, problem solving abilities, conceptual understanding, acquisition of language, moral understanding, and identity formation.

Questions addressed by developmental psychologists include the following: Are children qualitatively different from adults or do they simply lack the experience that adults draw upon? Does development occur through the gradual accumulation of knowledge or through shifts from one stage of thinking to another? Are children born with innate knowledge or do they figure things out through experience? Is development driven by the social context or by something inside each child?

Many theoretical perspectives attempt to explain development, among the most prominent are: Jean Piaget's Stage Theory, Lev Vygotsky's Social Contextualism, and the information processing framework. Historical theories continue to provide a basis for additional research, among them are Erik Erikson’s life-span stage theory, John Watson’s and B. F. Skinner’s Behaviorism, and a set of nested levels of context proposed by Urie Bronfenbrenner. Many other theories are prominent for their contributions to particular aspects of development. For example, Attachment theory describes kinds of interpersonal relationships and Lawrence Kohlberg describes stages in moral reasoning.

Developmental psychology informs several applied fields, including: educational/school psychology, child psychopathology, and developmental forensics. Developmental psychology complements several other basic research fields in psychology including social psychology, cognitive psychology, and comparative psychology.