Stereotypy is one of the defining characteristics of autism spectrum disorders (ASD) and can significantly interfere with an individual's development and acquisition of knowledge and skills as well as distract from and disrupt educational environments. Numerous behavioral interventions have been implemented by researchers in an attempt to reduce or eliminate such behaviors, including antecedent aerobic exercise. Research studies conducted on using antecedent aerobic exercise as an effective intervention to decrease stereotypy have been spread out over several years, and many of the studies are methodologically weak according to today's standards and guidelines for evidence-based practices. This study was conducted to replicate and extend previous research by examining the effect of aerobic exercise in the form of vigorous jogging for 10 consecutive minutes on the percentage of time two elementary-school-aged children with autism engaged in stereotypic behaviors during instructional activities in the morning (immediately following the aerobic exercise), with a secondary analysis evaluating potential residual effects later in the school day. A six-phase reversal (ABABAB) design was used to determine the presence of a functional relation between jogging and stereotypy. Upon visual analysis of graphed data, functional relations were apparent for both participants. Allison spent 12% less time engaging in stereotypic behavior immediately following the jogging sessions as compared to baseline, and Boyd’s stereotypic behavior decreased by 10.7% overall. There was no significant carryover effect to the instructional sessions two hours after the intervention. Measures of social validity confirmed that the intervention was easy to implement and perceived as beneficial. Implications for future research and practice are discussed.