This study explored the social-cognitive profile of 173 adults referred for an autism assessment. We considered key dimensional traits (autism, empathy and systemising) to understand social cognition in adults diagnosed with an autism spectrum condition compared with those who were referred for, but did not receive a diagnosis. There were no significant social cognitive differences between groups on measures of emotion recognition and social inference. Adults with a confirmed diagnosis, however, reported fewer empathising traits which were positively associated with social-cognitive understanding. Empathising partially mediated the relationship between diagnostic group and social-cognition. Lower empathising traits in individuals diagnosed in adulthood may be important in understanding challenges with social adaptability. The findings have implications for assessment and highlight the role of empathy in developing social understanding in autism.