About the authors -- Patricia Howlin is Principal Clinical Psychologist at the Maudsley Hospital, London, working mainly with autistic children and those suffering from pervasive developmental disorders. She is also Senior Lecturer in the Department of Child and Adolescent Psychiatry and Psychology at the Institute of Psychiatry, London. Michael Rutter is Honorary Director, MRC Child Psychiatric Unit and Professor of Child Psychiatry, in the Department of Child and Adolescent Psychiatry, Institute of Psychiatry, London. Both the principal authors have been involved in research and treatment with autistic children for many years. Their current research interests include a follow-up study of autistic individuals, and a comparison of young autistic adults and a matched group of individuals with severe early language delays. The genetic basis of autism is also being explored through a large scale family study of autism and a twin study of autism.