An explanation for the social dysfunction observed in Williams syndrome may be deficits in social cognition. This study explored aspects of social cognition in children with Williams syndrome with different genotypes. The 12 participants included one with a 1.1 Mb deletion that retained the GTF2IRD1, GTF2I, and GTF2IRD2 genes, seven with a 1.5 Mb deletion that preserved the GTF2IRD2 gene, and four with a 1.8 Mb deletion with loss of all three genes. The participant retaining all three genes was found to have better performance on social judgment and first-order theory of mind tasks than the group with loss of all three genes. These results may reflect the influence of the GTF2I gene family on social cognition in Williams syndrome.