Chronic pain in children is a significant public health problem globally and a leading cause of morbidity in children, with a negative impact on their emotional, physical and social development and function. The lives of families and caregivers are also significantly impacted. Chronic pain, defined as pain that persists or recurs for longer than three months, can be primary (independent of any identified biological or psychological contributing factor) or secondary to a clear, underlying etiology. Pain in children differs from that in adults for a number of physiological, developmental and social reasons, and thus data and research on, and clinical experiences with, adults may not be directly applicable to children. The management of chronic pain in children is complex and challenging, and there is a paucity of high-quality research studies on treatment interventions and management approaches. Pain management requires an approach that is tailored to each individual and context, and is multimodal and interdisciplinary, requiring trained healthcare providers and a coordinated, comprehensive, integrated response. In these guidelines, the World Health Organization (WHO) provides evidence-informed recommendations for the management of chronic pain in children. The recommendations are based on the most current, high-quality scientific evidence, and were formulated following processes and using methods that meet the highest international standards for guideline development. The recommendations in this guideline are based on systematic reviews of the evidence on benefits, harms, acceptability and feasibility, as well as on equity and resource considerations. The recommendations were formulated by the Guideline Development Group, consisting of individuals with diverse expertise and experiences and with global representation. The purpose of this guideline is to assist WHO Member States and their partners in developing and implementing national and local policies, regulations, pain management protocols and best practices. It will help countries balance concerns about ensuring access to appropriate therapies for pain relief with the harms arising from misuse of medications and other potential adverse effects of interventions for pain management. These guidelines focus on physical, psychological and pharmacological interventions for the management of primary and secondary chronic pain in children 0 to 19 years of age.