"The Autism Spectrum in the 21st Century" is the definitive guide to the autism spectrum, introducing the reader to key concepts and developments in diagnosis, psychological and biological research, theoretical models, evidence-based intervention, educational strategies and family issues. The book charts how developments in theory, research and practice have shaped, and continue to shape, the evolving concept of autism which is at the core of this field. The book explores: diagnostic principles and practice and their implications for prevalence; psychological functioning in autism, including sensory-perceptual, cognitive and socio-cognitive processes; genetics and brain function in autism, and the neurobiological basis for autism spectrum conditions; the range of therapeutic approaches available, including behavioral, communication-based and 'biological' interventions and their evidence base; educational implications, the options for individuals and families and the issue of inclusion; how autism affects the family unit; and, overarching issues and challenges for research, practice and people.