The aim of our study was to compare two neurodevelopmental disorders (Williams syndrome and autism) in terms of the ability to recognize emotional and nonemotional facial expressions. The comparison of these two disorders is particularly relevant to the investigation of face processing and should contribute to a better understanding of social behaviour and social cognition. Twelve participants with WS (from 6;1 to 15 years) and twelve participants with autism (from 4;9 to 8 years) were matched on verbal mental age. Their performances were compared with those of twelve typically developing controls matched on verbal mental age (from 3;1 to 9;2). A set of five tasks assessing different dimensions of emotional and nonemotional facial recognition were administered. Results indicated that recognition of emotional facial expressions is more impaired in Williams syndrome than in autism. Our study comparing Williams syndrome and autism over a small age range highlighted two distinct profiles which call into question the relationships between social behaviour/cognition and emotion perception. (Contains 2 tables and 3 figures.)