It has been estimated that 85% of all clinical research is wasted. Suboptimal outcome selection is an important cause of waste because it leads to research that cannot be compared and may not be clinically relevant. A solution to this problem is the use of a core outcome set, a standardised set of outcomes recorded whenever research in a specific field is carried out. The methodology behind developing a core outcome set and how this is being applied in the Core Outcomes in Neonatology (COIN) project is described.