Attention changes dramatically over the period of infancy and early childhood. Infants have poor vision at birth and attend primarily to salient physical characteristics of their environment. Attention in very young infants is influenced strongly by behavioral state, such that very young infants show nonspecific orienting only during their limited periods of alertness. Between about 3 and 18 months of age the development of alert, vigilant, sustained attention occurs. Sustained attention allows the focusing of processing resources and thus during this age infants begin to engage in active processing. Beginning at about 12 months of age, and continuing through early childhood and adolescence, a more voluntary, endogenously driven, executive control system begins to guide the deployment of attention. The early changes in attention are based largely on age-related changes in the brain, whereas later advances are impacted by the child’s experience and specific training activities. Advances in the fields of cognitive development, cognitive neuroscience, and psychophysiology have contributed to this knowledge.