There is growing evidence that insecurely attached children are less advanced in their social understanding than their secure counterparts. However, attachment may also predict how individual children use their social understanding across different relationships. For instance, the insecure child's social-cognitive difficulties may be more pronounced when the psychological states of an attachment figure are being considered. In the current study, forty-eight 4- to 5-year-old children were asked about their mothers' emotions and false beliefs, as well as those of non-attachment figures. The Separation Anxiety Test (SAT) was administered to assess children's attachment representations. Children's SAT scores predicted their overall performance on the false belief and causes of emotion tasks, even after controlling for age and verbal ability. More interestingly, however, children with high scores on the Avoidance dimension of the SAT experienced greater difficulty understanding maternal false beliefs relative to those of an unfamiliar adult female. Thus, although attachment insecurity may hinder social-cognitive development in general, the findings suggest that there are more specific effects as well. Attachment representations that are characterized by high levels of avoidance appear to interfere with children's ability to fully engage their social-cognitive skills when reasoning about maternal mental states.