Books on intellectual development typically separate development into distinct developmental periods: the formation of intelligence and basic cognitive skills that occurs until adolescence, and the maintenance, decline, or improvement of these intellectual skills across the adult life span. Robert Sternberg and Cynthia Berg have integrated research on these two development periods, by bringing together authors that provide a comprehensive overview to the major approaches to intellectual development. The authors draw on six different approaches to intellectual development through childhood or adulthood: psychometric, Piagetian, new-Piagetian, information- processing, learning, and the contextual perspectives. Common themes arise within, and across, particular perspectives, which suggests that a more unified view of intellectual development may emerge as boundary lines between perspectives and developmental periods diminish.