Background: Indiscriminate social approach behaviour is a salient aspect of the Williams syndrome (WS) behavioural phenotype. The present study examines approach behaviour in pre-schoolers with WS and evaluates the role of the face in WS social approach behaviour. Method: Ten pre-schoolers with WS (aged 3-6 years) and two groups of typically developing children, matched to the WS group on chronological or mental age, participated in an observed play session. The play session incorporated social and non-social components including two components that assessed approach behaviour towards strangers; one in which the stranger's face could be seen and one in which the stranger's face was covered. Results: In response to the non-social aspects of the play session, the WS group behaved similarly to both control groups. In contrast, the pre-schoolers with WS were significantly more willing than either control group to engage with a stranger, even when the stranger's face could not be seen. Conclusion: The findings challenge the hypothesis that an unusual attraction to the face directly motivates social approach behaviour in individuals with WS.