Recently, there has been a great deal of research on the socialization of children's emotions and self-regulation. In the present study, the specific strategies that mothers use to help their young children regulate their emotional responses were examined using a longitudinal design. Forty-three mother–toddler pairs were observed when toddlers were both 18 and 30 months of age, and mothers’ attempts to regulate their toddlers’ emotions during several emotion-eliciting tasks were transcribed from videotape. When the children were 5 years old, their responses to a disappointment task were observed. Results indicated a relation between mothers’ regulation strategies in toddlerhood and children's facial and behavioral responses to the disappointment task measured at 5 years of age. Specifically, mothers’ use of regulation strategies at 30 months, but not at 18 months, was positively related to children's appropriate emotional displays in response to disappointment. Moreover, the specific types of strategies that mothers used had differential associations to children's responses to disappointment. Findings are discussed in terms of the potentially important role of mothers’ behaviors in the development of children's emotion self-regulation.