Appropriate outcome measures and high-quality intervention trials are critical to advancing care for children with chronic pain. Our aim was to update a core outcome set for pediatric chronic pain interventions. The first phase involved collecting providers', patients', and parents' perspectives about treatment of pediatric chronic pain to understand clinically meaningful outcomes to be routinely measured. The second phase was to reach consensus of mandatory and optional outcome domains following the OMERACT framework. A modified Delphi study with 2 rounds was conducted including 3 stakeholder groups: children with chronic pain (n = 93), their parents (n = 90), and health care providers who treat youth with chronic pain (n = 52). Quantitative and qualitative data from round 1 of the Delphi study were summarized to identify important outcomes, which were condensed to a list of 10 outcome domains. Round 2 surveys were analyzed to determine the importance of the 10 domains and their relative ranking in each stakeholder group. A virtual consensus conference was held with the steering committee to reach consensus on a set of recommended outcome domains for pediatric chronic pain clinical trials. It was determined, by unanimous vote, that pain severity, pain interference with daily living, overall well-being, and adverse events, including death, would be considered mandatory domains to be assessed in all trials of any type of intervention. Emotional functioning, physical functioning, and sleep were important but optional domains. Last, the research agenda identifies several important emerging areas, including biomarkers. Future work includes selecting appropriate validated measures to assess each outcome domain.