Chronic pain in children is an increasingly recognized clinical problem with alarmingly high prevalence rates found in some populations. Although it is not understood why some children experience high levels of pain, the subjective experience of chronic pain (including its site, intensity, quality, unpleasantness, and associated suffering) has long been believed to result from interactions between multiple contributors, including nociceptive, affective, sociocultural, behavioral, and cognitive. Regardless of whether the antecedent of chronic pain is known or unknown, similar patterns of symptoms, behaviors, and disability are often seen. Historically, however, there has been an unhelpful tendency to dichotomize chronic pain as either physical or functional in origin. However, recent studies strongly support a biopsychosocial basis to all pain, revealing its sensory emotional nature by showing that large distributed neural networks are accessed during nociceptive processing. The development and maintenance of chronic pain involve long-term changes in multiple integrated peripheral, spinal, and brain regions interacting in a complex way to shape the individual's experience. Hence, chronic pain from any cause cannot be viewed as a purely physical or psychological phenomenon, nor should it be expected that a unimodal approach to treatment will succeed. It follows that when assessing children and young people with chronic pain, information on a wide range of developmentally relevant dimensions, conveniently classified as biological, psychological, and sociocultural, should be gathered to formulate the potential causes, contributors, and effects of pain to devise an appropriate multimodal management plan.