People with Williams syndrome (WS) are said to have sociable and extremely trusting personalities, approaching strangers without hesitation. This study investigated whether people with WS are less likely than controls to attribute negative intent to others when interpreting a series of ambiguous pictures. This may, at least partially, explain their hypersociability toward strangers. Twenty-seven individuals with WS and 54 typically developing controls (27 matched to WS participants on sex and chronological age and 27 matched on sex and mental age) viewed 10 ambiguous pictures, where one person in the picture may be seen as having a negative objective. Participants were asked to describe what was happening in the picture. Responses were scored for negative intention attribution (NIA). NIA was reduced in WS individuals relative to typically developing controls of the same chronological age, but was similar to typically developing controls of the same mental age. Findings are discussed in relation to possible underlying neurological and cognitive mechanisms and practical implications for understanding and teaching stranger danger to people with WS. (Contains 3 figures and 1 table.)