The Gilliam Asperger Disorder Scale is a norm referenced test designed to evaluate children with unique behavioral problems who may have Asperger’s Disorder. Based on the most current and relevant definitions and diagnostic criteria of Asperger’s Disorder, the GADS is useful for contributing valuable information toward the identification of children who have this disorder. Easily completed by a parent and professional who knows the child, the GADS provides documentation about the essential behavior characteristics of Asperger’s Disorder necessary for diagnosis. It can be used with confidence in the assessment process, documenting behavioral progress, targeting goals for IEPs, and for research purposes. The validity of the GADS was demonstrated by (a) confirming that the items of the test are directly related to the definitions of Asperger’s Disorder; (b) the subscales are strongly related to each other and the overall diagnosis of Asperger’s Disorder; and (c) the GADS scores discriminate persons with Asperger’s Disorder from persons with autism and other behavioral disorders.