Children with diffuse lung disease, also called childhood interstitial lung diseases (chILD), may have one of more than 200 entities, the biggest group of respiratory orphan lung diseases. Frequently undiagnosed because of lack of awareness or complex differential diagnosis, they lead to much morbidity, mortality (about 15%) and psychosocial stress for the families. Current lack of evidence based guidelines reflects the absence of any real scientific evidence for management. All current therapeutic options are off label.We propose that leading European clinical scientists and paediatric pulmonologists collaborate to assemble cohorts in which children with well defined disease entities, verified by international panels of clinicians, radiologists, geneticists and pathologists are followed in a pan-European database and biobank compatible with others worldwide to allow common projects. Outcomes and treatment schemes will be rigorously defined and their value systematically assessed. We will put defined treatment protocols systematically into practice to allow their evaluation and perform a randomised controlled trial in line with the EU recommendations, to put prescribing for children on an evidence based footing. This will give evidence to use medicines available based on their objectively determined effects and side effects. The project will lead to accepted evidence-based and consensus-agreed diagnostic and management clinical guidelines, to a better care of patients afflicted by rare chILD and lead to improved quality of life for children with these incurable diseases.