Aggression in early childhood has been found to predict future psychopathology, academic problems, and delinquency. In a sample of 136 mother-child pairs (M[subscript age] = 4 years, 11 months, SD = 11 months, 58% boys) associations among mothers' responding with distress to children's negative emotions, children's emotional control, and children's physically aggressive behaviours were explored. Children's emotional control problems mediated the relation between mothers' distress responses and children's physical aggression--higher levels of distress responses by mothers to children's negative emotions were associated with increases in emotional control problems in children, which in turn were associated with higher levels of children's physical aggression. Contrary to expectations, children's negative emotionality (i.e. temperament) did not significantly moderate the association between mothers' responding with distress to children's negative emotions and children's emotional control problems. Results emphasize the importance of focusing on children's emotional control skills and adaptive maternal responses to children's negative emotions.