Sleep state organization in the neonatal period was compared for groups of fullterm, preterm, and small-for-gestational-age infants. Preterm and small-for-gestational-age groups were found to have greater rates of state change than the fullterm group, and maternal perception of the infants was found to be negatively correlated to rates of state change in the preterm infants. Small-for-gestational-age infants had more active sleep without rapid eye movements than fullterm or preterm infants. The findings are discussed with regard to implications for CNS organization and possible early identification of infants at risk of developmental problems.