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.