Background: The two most common neurodevelopmental disabilities in children (ages 3-9 years) and adolescents (ages 10-19 years) in the United States are attention-deficit hyperactivity disorder (ADHD) and autism. Both disabilities pose major public health concerns because they can significantly interfere with an individual’s development or functioning (how one interacts with others, communicates, learn, and behave). Currently, there is no known single best intervention, treatment, or support service to strengthen or lessen the characteristics of ADHD or autism. Additionally, ADHD and autism are highly heterogeneous both between and within individuals and track into adulthood requiring support services throughout an individual’s entire lifespan. Popular support services for ADHD and autism include behavioral and pharmacological interventions, however, emerging evidence suggests physical activity may also be effective. Physical activity is widely accepted as essential for the growth, development, and overall physical and mental health of both neurotypical and neurodivergent children. Studies have also shown that physical activity can be utilized to improve outcomes related to the characteristics of ADHD, autism, and anxiety, which are highly prevalent in both disabilities. One popular support service for children with ADHD and/or autism is equine-assisted services (EAS). The key mechanism for improving outcomes in EAS is still not fully understood, although it is thought that it may be the human-animal bond. A less recognized benefit of EAS may be the naturally occurring physical activity during sessions. It seems plausible that physical activity could be a key mechanism of improvement in EAS for neurodivergent communities. However, physical activity is not typically measured in these interventions. Additionally, while parents generally perceive EAS as positive for their child, their perceptions of physical activity during EAS sessions remains unknown. Therefore, the purpose of this study was to examine the physical activity characteristics of a current EAS program and to understand parental perceptions of the benefits of EAS in neurodivergent children and adolescents. In addition, we examined the feasibility and acceptability of an EAS summer camp program infused with additional physical activity for neurodivergent children and adolescents. Methods: Participants were recruited from a non-profit organization that provides equine-assisted adaptive riding programs and services to children and adolescents with and without disabilities. All parents with children enrolled in the Fall 2023 12-week program or July 2024 1-week summer camp were eligible to participate in this study. Child and parent/guardian anthropometric, demographic, and perception data were collected through an online questionnaire hosted by Qualtrics (Qualtrics, Provo, UT). Participants’ physical activity was assessed during sessions with two Actigraph accelerometers (GT3X+, wGT3X+BT; Actigraph, LLC, Pensacola, FL), one at the waist and one on the wrist. The Movement and Observation in Children and Adolescents direct observation system was used to directly observe recorded equine-assisted adaptive riding sessions. Additionally, a questionnaire including both fixed and open-ended questions was used to examine parent and instructor perceptions concerning acceptability of the intervention. Results: Parents (n=12) reported that the naturally occurring physical movement/physical activity during sessions was beneficial for their child. Further, parents identified that weekly sessions significantly contributed towards meeting both muscle- and bone-strengthening activity while identifying less strongly that equine sessions contributed to the total amount of daily MVPA or aerobic activity. Concerning physical activity dosage, the average length of sessions was just over one hour in length (62.2 ± 12.9) and the participants spent the majority of their sessions in light physical activity according to the accelerometers (65.8%). However, direct observation showed the participants spent the majority of their sessions in moderate physical activity (62.2%). Both physical activity measurement methods showed child participants spent very little time sedentary or in vigorous physical activity. Concerning acceptability of infusing additional physical activity into sessions parents and instructors reported they were extremely satisfied with the intervention while preliminary efficacy showed no statistically significant change in sedentary behavior (W=16, p = 0.8) but borderline statistically significant trends for light (W=26, p = 0.052), moderate (W=2, p = 0.052), vigorous (W=0, p = 0.059), and moderate-to-vigorous physical activity (W=2, p = 0.052) according to wrist-placed accelerometers. For the waist-placed accelerometers, no statistically significant change in sedentary behavior (W=14, p = 1.0) light (W=17, p = 0.673), moderate (W=9, p = 0.0447), or total moderate-to-vigorous physical activity (W=9, p = 0.0447). However, there was a borderline statistically significant change in vigorous physical activity (W=0, p = 0.059). Conclusion: Our findings indicate that parents may be inherently aware that physical activity itself is one of the key mechanisms driving positive benefits for their child. Additionally, parents perceive equine-assisted adaptive riding as a setting that provides their child the opportunity and access to be physically active, where their child is happy and eager to participate and as a setting that combines physical activity with other powerful key mechanisms driving health benefits: the human-animal bond, being outdoors, and social interaction with staff and other children. Additionally, our results indicate that children spent nearly the entire equine-assisted adaptive riding session in either light or in the low end of moderate physical activity. Concerning infusing additional physical activity into equine-assisted adaptive riding sessions, adding active games and active recreation to equine-assisted adapted riding sessions led to a trending increase in some physical activity intensities. However, given the significant amounts of physical activity already occurring during sessions and children’s high level of motivation to participate as-is, future research should consider costs/benefit of adding PA to these sessions.