http://www.mentalhealth.org/publications/allpubs/CA-0009/default.asp
SAMHSA's National Mental Health Information Center, Center for Mental Health Services
This is one of a series of fact sheets on the mental, emotional, and behavior disorders that can appear in childhood or adolescence. Autism is one of the mental, emotional, and behavior disorders that appears in early childhood. Autism, or autistic disorder, almost always develops within the first 3 years of a child's life.