"Clinical trialists often struggle when trying to choose the outcomes to measure which would be of most use to the patients, practitioners and policy makers who will use their research to help them make decisions. These difficulties are passed on to those producing and reading systematic reviews, many of whom have experienced the frustration of finding that the original researchers either did not measure certain outcomes or measured them in such different ways that it is difficult or impossible to compare, contrast or combine the studies.A core outcome set is a set of outcomes which should be measured and reported, as a minimum, in all clinical trials for a specific condition. Core outcome sets (COS) could have implications across all areas of health research, reduce heterogeneity between trials and lead to research that is more likely to have measured relevant outcomes. COS would enhance the value of evidence synthesis by reducing the risk of outcome reporting bias and ensuring that all trials contribute usable information.The COMET (Core Outcome Measures in Effectiveness Trials) Initiative aims to develop an international network of individuals and organisations interested in the development, application and promotion of core outcome sets. Working together will enable COS to be developed efficiently, leading to improvements in the quality of clinical research much earlier than would otherwise be the case. The objective of this proposal is to develop COMET’s strategic plan to: (i) increase the number of COS developed using evidence-based methods, (ii) increase their impact on the quality of research-based knowledge, by raising awareness and increasing implementation, (iii) establish methods for standards of COS development.COS will shape the future of European and international clinical trials practice, increasing the efficiency and value of the research process by reducing the inefficiencies of trials of similar topics measuring outcomes in different ways."