Citizen Science can result from various recipes, and notably from a participative or a collaborative process. Some institutions collaborate with amateurs for their research and together produce data that nourish science. Some are good at consulting citizens on their tastes, but lack a common menu for their projects. Some are experiencing both approaches but have not yielded results yet. This session will present approaches at work in three institutions (in Spain, Denmark and Belgium) and will give the floor to the audience to collect other experiences in Citizen Science. Together we will try to increase appetite for Citizen Science projects between research institutions, science centres, decision makers and civil society.