Pediatric caregivers and parents are eager to know the role of proton beam therapy (PBT) in the treatment of children with brain and solid tumors and other diseases for which radiation therapy is indicated. Although the number of children treated with PBT for the most common pediatric tumors is relatively small and outcome data are clearly lacking, modeling radiation dose, volume, and outcomes based on photon benchmark data and clinical experience suggest an advantage for PBT and an opportunity to reduce or eliminate many of the early and late effects of radiation therapy. As the number of centers available to treat children increases, it is incumbent on those with access to this modality to optimize other critical aspects of radiotherapy and cancer care and follow-up that are requisite to achieving disease control and high-quality survivorship. Even though the focus of pediatric radiation oncology is weighted toward side effect reduction, there is an opportunity for dose escalation or biologically optimized radiotherapy in a number of diseases or settings in which high-dose irradiation is considered unapproachable. Justification for PBT in pediatric patients should be realized once the costs of treating acute symptoms, growth hormone deficiency, orthopedic deformities, and secondary malignancies are studied and reduced.