We are obligated to protect individual child subjects of research, yet it is also necessary to investigate the safety and efficacy of medical treatments that benefit children as a class. The federal regulations on research with children have provided ethical guidance since 1983, but divergent interpretations persist. Since varying interpretations can lead to confusion and abuses, efforts are underway to clarify the criteria. Clarity is needed to protect individual child subjects from harm while enabling ethical research to proceed. The "pediatric rule" and the "pediatric exclusivity" incentive are important policy initiatives for promoting sound research on the medical treatment of children.