ABSTRACT The parent grant’s scope is to establish feasibility and acceptability of a novel approach to increase overweight / obese adolescents’ physical activity by leveraging their attachment to the family dogs; and to collect pilot data to establish the effect size of an empirically validated BodyWorks program (Borden et al., 2012; DHHS, 2013) enhanced with a Canine Health Literacy module that parallels the BodyWorks humans - only curriculum. The theory of change links an increase in the adolescents’ health literacy about both human and canine physical activity and nutritional needs to more positive affect in the presence of the dog during physical activity (Liao et al., 2017), which is expected to lead to an increase in physical activity. The scope of the proposed administrative supplement remains the same as in the parent grant, however, the population will be broadened to include both public and private insurance patients receiving care in specialty clinics at Children’s Hospital Los Angeles (CHLA) and in CHLA-affiliated general pediatrics and specialty community clinics. In the parent grant, only publicly insured patients receiving healthcare at the FQHC AltaMed clinics in the CHLA geographical area have been included in the project, which limited recruitment already disrupted by the COVID-19 pandemic. Specifically, the funding will allow to add 17 additional clinics, extending recruitment beyond the 5 FQHC AltaMed clinics to a total of 22 recruitment sites. The aims of the study are: Specific Aim 1: Test the feasibility and acceptability of a concurrent approach using physical activity trackers and Ecological Momentary Assessment. 2(a): Test the feasibility and acceptability of objective measurement of physical activity using wireless fitness trackers for adolescents (FitBit Ace), their parents (FitBit Flex2), and their dogs (FitBark); 2(b): Test the feasibility and acceptability of using mobile phones for Ecological Momentary Assessment of types and contexts of adolescent's physical activity with dogs. Specific Aim 2: To establish the size of the effect, and the variability associated with the 7 week-long BW + CHL module, as compared with the control group who received the standard BW program in 3(a) adolescents' positive affect during or after physical activity with the dog, as measured by the Ecological Momentary Assessment using prompts on mobile phones; and 3(b) levels of overall physical activity for the adolescents, their parents, and the dogs as measured by the FitBit Ace (adolescents), FitBit Flex2 (parents), and FitBark (dogs). The project will establish feasibility, acceptability, attrition, and protocol compliance, and will collect pilot data needed for power calculations in preparation for an R01 Randomized Controlled Trial as a next step to test the effectiveness of our enhanced BW+CHL program. This project represents a significant methodological and theoretical advancement in the field of Human-Animal Interaction (HAI) and i...