In this review, we argue that perceived diagnostic uncertainty in idiopathic pediatric chronic pain patients and their parents is critically important for understanding pain cognitions, behavioral responses to pain, treatment choices, and outcomes during this developmental period. We include evidence from children (under 12 years) and adolescents (12-18 years). This period sets the stage for future experience of pain: two thirds of children and adolescents with chronic pain will become adults with chronic pain . The prevalence of pediatric chronic pain is rising, and has been described as a growing epidemic . Better understanding of this core issue through well-designed research with pediatric populations is therefore crucial.