Citizen engagement is being promoted in many countries as a mechanism to improve the efficiency, quality and relevance of research and improve transparency and trust in science. At the same time, digitalisation is opening up new opportunities for consultation and exchange with citizens. This report includes an analysis of 7 different initiatives to engage citizens in the co-design of research agendas . These cases varied considerably in their scientific focus, geographic scale and overall aims and methodology. Nevertheless a number of consistent messages came through in relation to: 1. the rational for engaging citizens in setting research agendas; 2. how to do so effectively; 3. the resource implications and potential impact. The report includes 10 key observations or lessons learned to help guide policy-makers, research funders and researchers who are interested in citizen engagement in science.