While the cause of chronic pain is clear for some, many children and adolescents experience ongoing pain without an obvious explanation or evidence of underlying pathophysiology. Diagnostic uncertainty is experienced by over a third of youth with chronic pain and their parents.  In the context of pediatric chronic pain, diagnostic uncertainty may present as challenges to the clinician in providing a pathophysiological cause and diagnostic label that clearly explains pain and pain-related disability, as well as patients’ perceptions that a label and explanation for their pain are missing or inaccurate. Diagnostic uncertainty, by definition and through qualitative investigations of children’s and parents’ lived experiences,  develops in the social context of family-clinician interactions through which a label, diagnosis, or explanation for pain is offered. Dr. Neville will discuss the social phenomenon of diagnostic uncertainty and how it is shaped by aspects of the clinical encounter, including the explanations provided for pain and (in)validation from clinicians. She will present new empirical data investigating diagnostic uncertainty across the pain care journey. Lastly, using international survey data, she will discuss how changes in diagnostic uncertainty over time are linked to youth pain outcomes.