The CHARGE Study (Childhood Autism Risks from Genetics and the Environment) is a case-control study of 2,000 children with differing patterns of development. These include children with autism, children with developmental delay but not autism, and typically developing children. Subject groups will be compared with regard to a broad array of exposures and physiologic factors. Austism cases will also be characterized into more homogenous subgroups to determine whether particular genes or environmental exposures are associated with certain subtypes of this condition.