The study will concern the health professionals who takes care of adolescents suffering from chronic (non-malignant) musculoskeletal pain. In France, the medical specialities concerned are paediatric medicine, rheumatology, pain medicine, adolescent medicine and psychiatry. The investigators also want to include participants from paramedical fields: physiotherapists, ergotherapists and psychologists. The participants will be selected in the large repository of the professionals working with the French National Reference Center in Paediatric Rheumatology and Inflammatory Diseases