In this study, the heart rate response of children with and without autism spectrum disorder (ASD) exposed to outdoor free play sessions during preschool was examined. Participants (n = 7; four children with ASD and three children who show typical development) wore Actiheart heart rate monitors during 6 school days. Using a single-subject design, the researchers found that children with and without ASD demonstrated a similar heart rate response to an outdoor free play period and similar participation as measured using PAHR-25 and PAHR-50 indexes. These children did not engage in adequate amounts of moderate to vigorous physical activity during free play. Thus, interventions should be developed to determine best practices for children with and without ASD to participate in adequate amounts of moderate to vigorous physical activity during free play.