This chapter reviews the developmental trajectories of specific cognitive and neuropsychologic functions. Piaget observations regarding children's abilities to think, reason, and perceive their world have had a tremendous impact on the conceptualization of cognitive maturation. Piaget conceptualized cognitive development as consisting of a sequence of stages, although it is important to emphasize that he envisaged a continuity of development over its entire course. Piaget's description of the sensorimotor and preoperational stages provides some insight into the development of attention. The ceilings for maturation of various cognitive functions have been identified to be around the ages of 10 to 12 years, but this may simply reflect the limitations of neuropsychologic tests. Neuroimaging studies have shown that the brain continues to undergo striking reorganization even in the adulthood. Functional neuroimaging holds great promise for mapping the brain maturational changes underlying neuropsychologic development in children and adolescents.