STOP-JIA is a PCORI funded prospective observational study which will compare the clinical effectiveness and impact on patient reported outcomes of 3 Childhood Arthritis & Rheumatology Research Alliance (CARRA) consensus derived treatment strategies (CTPs) in new-onset polyarticular JIA (pJIA) patients to answer the critical question of when is the best time to begin biologic medications to achieve the optimal clinical and patient reported outcomes. Because the CARRA Registry will be used for data collection, all patients will be enrolled in the CARRA Registry. The standard of care treatments are chosen by the treating physician and patient/caregiver and are not randomized.