Research in developmental psychology—which examines the history, origins, and causes of behavior and age-related changes in behavior—seeks to construct a complex, multi-level characterization of behavior as it unfolds in time across a range of time scales, from the milliseconds of reaction time to the days and weeks of childhood, the decades of the human lifespan, and even beyond, to multiple generations. Behavior, in this view, is embedded within what is essentially a dynamic system of relations extending deep within individuals. Thorough and engaging, this handbook explores the impact of this research on what is now known about psychological development, from birth to biological maturity, and it highlights the extent to which the most cutting-edge developmental science reflects a new kind of intellectual synthesis: one that reveals how cultural, social, cognitive, neural, and molecular processes work together to yield human behavior and changes in human behavior. With insightful contributions from more than 50 of the world's leading developmental scientists, these two volumes will serve as an influential and informed text for students and as an authoritative desk reference for years to come.