The 20th century heralded major advancements in pediatric health care including vaccinations, antibiotics, and sophisticated radiographic studies. These interventions led to substantial improvements in child mortality. Yet, as medical interventions became more commonplace, concerns about negative health effects developed. As a result, many of the changes to pediatric practice in the 21st century have actually involved deimplementation, the process of reducing care that is harmful, ineffective, overused, or not cost-effective. Despite this progress, many practices persist that are not supported by evidence. This Viewpoint explores the historical drivers of deimplementation and proposes ways to further reduce the amount of low-value care delivered to children.