OBJECTIVES: Beginning in 2013, the North American Society of Pediatric Gastroenterology, Hepatology and Nutrition (NASPGHAN) sponsored and developed subspecialty field-specific quality improvement (QI) activities to provide Part 4 Maintenance of Certification (MOC) credit for ongoing certification of pediatric gastroenterologists by the American Board of Pediatrics. Each activity was a Web-based module that measured clinical practice data repeatedly over at least 3 months as participants implemented rapid cycle change. Here, we examine existing variations in clinical practice among participating pediatric gastroenterologists and determine whether completion of Web-based MOC activities improves patient care processes and outcomes. METHODS: We performed a cross-sectional and prospective analysis of physician and parent-reported clinical practice data abstracted from Web-based MOC modules on the topics of upper endoscopy, colonoscopy, and informed consent collected from pediatric gastroenterologists from North America from 2013 to 2016. RESULTS: Among 134 participating pediatric gastroenterologists, 56% practitioners practiced at an academic institution and most (94%) were NASPGHAN members. Participating physicians reported data from 6300 procedures. At baseline, notable practice variation across measured activities was demonstrated. Much of the rapid cycle changes implemented by participants involved individual behaviors, rather than system/team-based improvement activities. Participants demonstrated significant improvements on most targeted process and quality care outcomes. CONCLUSIONS: Pediatric gastroenterologists and parents reported baseline practice variation, and improvement in care processes and outcomes measured during NASPGHAN-sponsored Web-based MOC QI activities. Subspecialty-oriented Web-based MOC QI activities can reveal targets for reducing unwarranted variation in clinical pediatric practice, and can effectively improve care and patient outcomes.