Autism Spectrum Disorder (ASD) is a pervasive developmental disorder in which individuals experience deficits in communication, restricted, repetitive patterns of behavior, as well as social interaction and reciprocity (American Psychiatric Association, 2013). For adolescents with autism, anxiety often interferes with these symptoms making them more pronounced. When compared with normative community samples, children and adolescents with autism display elevated levels of anxiety (MacNeil, Lopes & Minnes, 2008). The presence of anxiety can create more difficulties for children with autism such as increased self-injurious behaviors, depressive symptoms, gastrointestinal issues and social skills deficits leading to increased family stress and health care needs (Kerns et al., 2016). Diagnostic overshadowing and a lack of sound diagnostic criteria often results in symptoms of anxiety being overlooked within the ASD population. However, atypical behaviors such as self-stimulatory and stereotyped behaviors, which are common features of autism, can be increased by the presence of anxiety. Furthermore, given children with autism struggle to identify emotions in themselves and others inaccuracy in reporting can cloud a clinician's ability to provide a comorbid diagnosis of anxiety (MacNeil, Lopes & Minnes, 2008). Research suggests that exercise interventions have been used in non-clinical and clinical anxiety disorder samples and demonstrate significant reductions in anxiety, improved overall wellbeing and cardiovascular health (Stubbs, 2016). Minimal research has been conducted to replicate these findings on children with autism. Research on children with autism and exercise has found behavioral improvements such as reduction in stereotyped and self-stimulatory behaviors as well as reduced aggression, reduced self-injury and reduced classroom disruptive behaviors. In relation to academics, research states increases in the amount of time on task, increases in responses to academic problems and increased accuracy to academic questions and improvements in vocabulary abilities following exercise (Lang et al., 2010). By reducing anxiety and atypical behaviors, a child with autism is more available for learning and emotional regulation within an academic setting as well as community setting (Rosenthal-Malek & Mitchell, 1997). The current study utilized a six week exercise intervention five 12 to 17 year old individuals with autism hypothesizing reductions in short and long term anxiety levels and atypical behaviors as reported by the individuals, parents and teachers on the Behaviors Assessment System for Children, Third Edition (BASC-3; Reynolds & Kamphaus, 2015) and the Faces Anxiety Scale (McMurtry, Noel, Chambers & McGrath, 2010). All participants must had a medical diagnosis of autism spectrum disorder, level 1 or 2, presented with symptoms of anxiety or atypicality such as self-stimulatory behaviors and did not have any physical limitations preventing them from participating in exercise. The study hypothesized that short term reductions in anxiety will be seen before and after each session as reported on the Faces Anxiety Scale while long-term reductions in anxiety and atypical behaviors will be observed from the beginning of the intervention to the end of the six weeks as seen on the BASC-3 at home as reported by the parent, at school as reported by the teacher and by the participant in various environments in their life. Results demonstrated insignificant effects for most participants in analyses such as correlation and percentage exceeding the median. One participant was able to identify short term changes in anxiety levels before and after each session while the other four participants felt no differences. Additionally, teachers were not able to find any changes in atypicality or anxiety across all participants. Parents and participants indicated isolated decreases in anxiety and atypical behaviors throughout the baseline and intervention sessions but not at a significant level. When looking at changes in behavior at a group level across both dependent variables, anxiety and atypicality, participants improved at a significant rate as reported by parents and self, however, similar results were not found for teacher. Significant findings regarding the maintenance of effects could not accurately assessed given the abbreviated length of the follow up phase. Therefore, it is not possible to interpret if these findings had a long term effect on anxiety and atypicality levels. The importance of these findings as it relates to services for children and adolescents with ASD is discussed. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]