Asperger's Syndrome is assumed to be closely related to autism. A case of a 21-yr-old man with Asperger's Syndrome who is frequently violent to his 71-yr-old girlfriend is presented. According to a social-cognitive model of autism, this man is predicted to be markedly impoverished in his appreciation of his victim's thoughts and feelings. Interview-based assessments confirm this deficit, and this is discussed as an important factor in the maintenance of his violence.