 The core outcome set standards for development, COS-STAD, project has established 11 minimum standards to be followed by COS developers when planning their projects and by users when deciding whether a COS has been developed using reasonable methods. These standards include the scope of the COS, the stakeholders involved in its development, and the consensus process used to reach agreement among them. This article was authored by Jamie J. Kirkham, Catherine Davis, Douglas G. Altman and others.