Reviews research on the construct of emotion regulation in young children. The lack of consensus with regard to a definition of emotion regulation notwithstanding, it appears that biological and behavioral processes involved in emotion regulation can be reliably measured early in life. Such indices of reactivity may be useful in identifying children at risk for developmental psychopathology, but the predictive utility of these indices has yet to be established. Measurement issues and factors hypothesized to affect an infant’s risk for dysregulation, such as care-giving factors, are presented. The implications of continued programmatic research on emotion dysregulation early in life are discussed.