Child development involves both reactive and self-regulatory mechanisms that childrendevelop in conjunction with social norms. A half-century of research has uncovered aspects ofthe physical basis of attentional networks that produce regulation, and has given us someknowledge of how the social environment may alter them. In this paper, we discuss six forms ofdevelopmental plasticity related to aspects of attention. We then focus on effortful or executiveaspects of attention, reviewing research on temperamental individual differences and importantpathways to normal and pathological development. Pathologies of development may arise whenregulatory and reactive systems fail to reach the balance that allows for both self-expression andsocially acceptable behavior. It remains a challenge for our society during the next millennium toobtain the information necessary to design systems that allow a successful balance to be realizedby the largest possible number of children.