In the search to understand autism, many research programs have begun looking at younger siblings of children with autism. While your child most likely does not have a diagnosis of autism, past family studies have found that siblings of a person with autism are at a higher risk for having autistic disorder than members of the general population. Most recently, results from our MRI study of brain development in 2 year olds showed that brain enlargement is already present at a young age in children with autism. The data collected suggest that brain overgrowth may begin as early as 12 months of age, if not earlier. This current project aims to identify very early brain features that may be characteristic of infants at risk for autism.