Temperament is an ancient concept. Since the time of Vindician (Diamond, 1974), it has been used to establish conceptual links between behavior and the constitution of the individual. Temperament also has much to offer the modern student of development. It gives us a place to begin thinking about the origins of cognitive and affective structures, and a framework for relating these structures to underlying physiological systems of reaction and regulation. It gives us a place to begin tracing the developing patterns of experience that constitute the lives of individuals.