Important advances have recently been made in studying emotions in infants and the nature of emotional communication between infants and adults. Infant emotions and emotional communications are far more organized than previously thought. Infants display a variety of discrete affective expressions that are appropriate to the nature of events and their context. They also appreciate the emotional meaning of the affective displays of caretakers. The emotional expressions of the infant and the caretaker function to allow them to mutually regulate their interactions. Indeed, it appears that a major determinant of children's development is related to the operation of this communication system. Positive development may be associated with the experience of coordinated interactions characterized by frequent reparations of interactive errors and the transformation of negative affect into positive affect, whereas negative development appears to be associated with sustained periods of interactive failure and negative affect.