Value-based care is a health care delivery model in which practitioner payment is based on measures of health care quality, practitioner performance, and patient experience. Accountable care organizations (ACOs), which aim to improve quality and reduce cost through population health management and value-based payment arrangements, are one of the most widespread health care reform models in the US. Although ACO development and innovation have mainly focused on older adults insured by Medicare, 14 states have now implemented Medicaid ACOs that serve both adults and children. As ACOs continue to expand, there is a growing need to understand how these care and payment models can best promote child health and account for children’s distinct health care needs, particularly for the nearly 40% of US children insured by Medicaid and those enrolled in mixed-age (non–pediatric-focused) ACOs.