Juvenile idiopathic arthritis (JIA) is the most common rheumatologic disease in children. The main symptoms of JIA, which are often the primary focus of treatment, include joint swelling, stiffness, and tenderness. Additional symptoms can include malaise, fatigue, and pain. However, the exact mechanisms contributing to pain are not yet fully understood. Participants will complete a 2.5-hours study session. In the study session, psychophysical assessments of thermal and pressure stimuli will be performed. In addition, demographic, social, pubertal maturation, and behavioral and psychological factors will be collected via questionnaires. A saliva sample and/or blood draw may occur for the analysis of various immune factors and sex hormones. If a joint aspiration is done as part of their standard of care, we will request a sample of the synovial fluid for analyses of immune, hormonal and/or genetic factors. Participants will have the option to participate in additional optional follow-up study visits (every 3 months, up to 1 year) and to complete monthly surveys asking about their juvenile arthritis.