Juvenile idiopathic arthritis (JIA) presents with diverse symptoms and complications, making early and effective treatment challenging. The JACKPOT (Juvenile Arthritis–Compiling Knowledge for Personalized Outcomes and Treatment) study aims to identify clinical, imaging, and biologic markers present early in disease that predict which children will achieve clinically inactive disease and avoid long-term damage. Using a well-characterized cohort of children with JIA, the study integrates musculoskeletal ultrasound, biosample analysis, and patient-reported outcomes to understand disease courses. Findings will inform personalized treatment strategies and support future large-scale studies, ultimately improving outcomes and quality of life for children with JIA.