The purpose of this research was to investigate if motor skills could be used as a differentiating feature between Asperger's Disorder (AD) and High Functioning (HFA) in children under the age of 9 years, 0 months, in order to provide additional information regarding the usefulness and validity of distinguishing these two disorders. There is continued controversy over whether the two disorders differ because there is a lack of a consistent set of diagnostic instruments and criteria for clinicians to use when diagnosing disorders within the autism spectrum. The research design employed was a non-experimental, causal comparative study. The study's methodology involved randomly selecting a sample population from a database of archived records of individuals who met the special education eligibility criteria for autism maintained by Clark County School District in Las Vegas, Nevada. Forty-six records were identified as matching the study parameters and comprised 10 girls aged 3-6 and 36 boys aged 3-7 years. The data was analyzed using the SPSS statistical software package. The independent "t" test was used to test the significance of the difference between the means of the two groups in the study. The results revealed that, with respect to motor skills, there was a significant difference between the AD and HFA groups. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]