Cognitive performance and the relationship between theory of mind (TOM), weak central coherence and executive function were investigated in a cohort of young people with additional learning needs. Participants were categorized by social communication questionnaire score into groups of 10 individuals within the autistic spectrum disorder (ASD) range, 14 within the pervasive developmental disorder range and 18 with few autistic traits. The ASD group were significantly poorer than the other groups on a test of cognitive flexibility. In the ASD group only, there was a strong relationship between executive performance and TOM which remained after controlling for IQ. Our findings suggest that the relationship between cognitive traits may more reliably distinguish autism than the presence of individual deficits alone.