Abstract Chronic musculoskeletal (MSK) pain affects the lives of over a quarter of youth, with societal costs exceeding $19.5 billion dollars in the U.S. each year. The impact of chronic MSK pain in adolescence is felt into adulthood and is a documented risk for opioid misuse. There are a number of efficacious behavioral interventions for adolescents with chronic pain, but many access-to-care barriers exist, highlighting the critical need to develop digitally delivered behavioral interventions to drastically increase reach. Graded exposure is a theory- driven, individually-tailored intervention for individuals with chronic pain targeting pain-related impairment by exposing patients to previously feared and avoided activities. This project seeks to develop and evaluate the feasibility and preliminary effectiveness of a digital exposure treatment (iGET Living) for adolescents with chronic musculoskeletal (MSK) pain and their parents, utilizing a sequential replicated and randomized single-case experimental design (SCED) and incorporating innovative technology for remote biomechanical assessment. The central hypothesis is iGET Living will be acceptable and feasible for youth with chronic MSK pain and their parents and will be effective at alleviating functional disability and pain-related distress. Agile research methods will allow for a rapid, iterative development and evaluation of the intervention, yielding a clinically useful solution. This proposal includes a comprehensive training plan under the guidance of mentors with expertise across study aims. Dr. Harrison will obtain specialized training in 1) user-centered design and agile development of digital interventions, 2) clinical research and trial execution, 3) intervention optimization, dissemination, and implementation science, 4) innovative, remote assessment of biomechanical function, 5) advanced qualitative and quantitative statistics, and 6) experiential learning in grant-writing. Research: Aim 1: In an iterative, user- experience design process, Dr. Harrison and her team will develop iGET Living for adolescents with chronic MSK pain and their parents. Data regarding comprehensiveness and acceptability will be collected via interviews with patients and parents. Clinicians specialized in pediatric chronic pain will provide feedback on how providers might integrate into practice, who they would refer, and potential barriers to utilization. Aim 2: Dr. Harrison will evaluate preliminary feasibility and effectiveness of iGET Living to reduce pain-related distress and functional disability utilizing SCED with multiple measures. Successful completion of these aims will provide the opportunity to rapidly evaluate treatment effectiveness and inform iterative development of iGET Living to prepare subsequent RCTs. The strong mentorship team, specialized career development training, and proposed research plan will allow Dr. Harrison to gain the expertise needed to seek R-level funding and achieve he...