Objectives/Goals: Pediatric obesity is a public health issue. Many youths in lifestyle obesity treatments do not improve their weight. Sequential Multiple Assignment Randomized Trial (SMART) study designs can support slow responders (e.g., youth who do not initially lose weight). SMARTs have limited use in pediatric obesity and lack data-driven adaptive rules. Methods/Study Population: This study leveraged an ongoing 6-month family-based health behavior pediatric obesity treatment for children and their parents. Parents with obesity and their children (6–11years) with overweight/obesity (body mass index >85th%ile) who lived in rural areas and were a part of the larger pediatric obesity treatment trial were invited to this study. During the treatment, parent/child dyads were asked to complete additional surveys across nine time points (weeks 1, 2, 3, 4, 6, 8, 12, 16, and 20). Surveys assessed the child’s physical activity, diet, and pain, along with the family environment and parental stress. The child’s anthropometrics were measured each month. Results/Anticipated Results: Data collection will be completed in December 2025. Anticipated results will include analyses to identify responders (i.e., children who reduce their weight outcomes [body mass index (BMI) z-score, BMI percentile, or weight]) and slow responders (i.e., children who do not reduce their weight outcomes) to the pediatric obesity treatment; based on preliminary work, we expect ~50% of the sample to be responders. Once responders/slow responders are identified, survey data will be used to define the adaptive rules, including the tailoring variable (e.g., physical activity or junk foods, or early-response weight outcomes) and decision time point for second randomization. Discussion/Significance of Impact: Data from this study will lay the groundwork for developing data-driven criteria for SMART rules (tailoring variable and decision time point for second randomization). This, in turn, will support the development of adaptive interventions to identify and support the many youths who are slow responders to lifestyle pediatric obesity treatments.