 The Child Health Care at Mata Pediatric Study, CHAMPS, Trial is evaluating whether a group model of well-child care for mothers with opioid use disorder, and their children can improve patient-reported satisfaction and adherence to recommended care. This study will compare the effectiveness of group well-child care versus individual well-child care for these families. This article was authored by Vanessa L. Short, Diane J. Abate Marco, Erica Seed, and others.