Within general psychiatry, awareness of autism spectrum disorder (ASD) and the use of the terms ‘autism’, ‘autistic disorder’, ‘Asperger syndrome’, the ‘autism spectrum’, and ‘high functioning autism’ (HFA) are growing. However, autism has yet to become part of the accepted mainstream, core curriculum of general psychiatry. Psychiatrists are now expected to be able to recognize autism and consider its effects on their adult patients, particularly those showing signs of comorbid mental disorder, for example, schizophrenia, personality disorder, mood disorder, or attention-deficit/hyperactivity disorder (ADHD). From childhood through to adulthood and old age there is a failure in autism to develop skills in reciprocal social interaction, understanding, and flexibility. This can profoundly affect behaviour in the community, personal independence, employability, and social relationships, including marriage and parenting. Most cases of autism in adults are unrecognized and undiagnosed, both within the general population and in adults using psychiatric services. This book gives a comprehensive introduction to autism and Asperger syndrome written to fit the adult clinician’s perspective. It will assist with autism recognition and diagnosis in adulthood. It is designed to enhance the clinician’s role in treating patients with co-morbid mental disorder, while understanding and taking account of the autism component. It will also help in signposting patients with autism to appropriate care and support, as family involvement diminishes, or ceases in adulthood and old age, and in the psychiatrist’s role in providing advice to the courts and in the context of detention in accordance with mental health law.