Interest in examining the underlying mechanisms of young infants' face-processing abilities is increasing; hence this paper presents a review of infants' abilities to recognize and respond to faces and their conveyed emotion as social stimuli different from other types of objects. A discussion on evidence from imitation, response to still faces, patterns of visual attention and social referencing suggests that infants have the ability to understand the meaning of faces even before they reach the age of one, and that this continues to develop during childhood. At the neurobiological level, this could be attributed to early maturation of the occipitotemporal cortex, amygdala and other cortical structures, and the delayed maturation of other structures and their connections. Evidence shows that the development of expression recognition and responses in infants is influenced strongly by experience.