Nearly 20 years ago, standards were established for hospitals to assess and treat pain in all patients. Research continues to demonstrate evolving trends in the measurement and effective treatment of pain in children. Behavioral research demonstrating long-lasting effects of inadequate pain control during childhood supports the concepts of early and adequate pain control for children suffering from painful conditions in the acute care setting. The authors discuss pain concepts, highlighting factors specific to the emergency department, and include a review of evidence for pharmacologic and nonpharmacologic treatments.