Prolonged pediatric fever is most often due to a self-limiting infectious illness, but can sometimes be a sign of much more serious disease. The care of children with prolonged fever can be challenging, since there is significant variation in the definition of prolonged pediatric fever, and evidence-based decision support tools to guide evaluation and management of children with prolonged fever are limited. This issue constructs a framework for initial emergency department evaluation and management of children with fever lasting ≥5 days and fever of unknown origin lasting ≥8 days.