To describe the selection, development, and implementation of quality measures (QMs) for juvenile idiopathic arthritis (JIA) by the Pediatric Rheumatology Care and Outcomes Improvement Network (PR-COIN), a multihospital learning health network using quality improvement methods and leveraging QMs to drive improved outcomes across a JIA population since 2011. An American College of Rheumatology-endorsed multistakeholder process previously selected initial process QMs. Clinicians in PR-COIN and parents of children with JIA collaboratively selected outcome QMs. A committee of rheumatologists and data analysts developed operational definitions. QMs were programmed and validated using patient data. Measures are populated by registry data, and performance is displayed on automated statistical process control charts. PR-COIN centers use rapid-cycle quality improvement approaches to improve performance metrics. The QMs are revised for usefulness, to reflect best practices, and to support network initiatives. The initial QM set included 13 process measures concerning standardized measurement of disease activity, collection of patient-reported outcome assessments, and clinical performance measures. Initial outcome measures were clinical inactive disease, low pain score, and optimal physical functioning. The revised QM set has 20 measures and includes additional measures of disease activity, data quality, and a balancing measure. PR-COIN has developed and tested JIA QMs to assess clinical performance and patient outcomes. The implementation of robust QMs is important to improve quality of care. PR-COIN's set of JIA QMs is the first comprehensive set of QMs used at the point-of-care for a large cohort of JIA patients in a variety of pediatric rheumatology practice settings.