What is the unique mission of developmental psychology? How has it evolved historically? What are its current challenges? The chapters in this collection present the view that research, history and policy are essential and interlocking components of a mature developmental psychology. Patterns of human development differ markedly across historical epochs, cultures and social circumstances. Major societal changes examined by contributing authors - the advent of universal compulsory schooling, the adoption of a one-child policy in China, US policy shifts in healthcare, welfare and childcare - present 'natural experiments' in social design. Authors challenge the idea of a clear distinction between basic and applied developmental research. In sharp contrast with the view that science is value-neutral, developmental psychologists have from the outset pursued the betterment of children and families through educational, childcare and health initiatives. An historical perspective reveals the beneficial, if sometimes contentious, interplay between empirical research and social programs and policies.