More and more people are aware of the importance of a good group dynamic to lead a collective project (especially in the context of social and cultural diversity) but these positive trends are often difficult to build. The seminar "From Singular to Plural" arose from the common determination of 3 European youth organizations dealing with popular and non-formal education (Nexes [Barcelona, Spain], Via Brachy [Toulouse, France] and European Village [Athens, Greece]) to share their experience in group facilitation and implementation of joint projects to identify good practices that meet their needs and those of many other actors of social innovation in Europe. The seminar took place in Gaillac (South-West France) from April, the 11th to April, the 16th of 2015. It brought together 28 people involved in collective projects of social interest in France, Greece and Spain. For 5 days, the participants shared their knowledge and expertise in group facilitation and questioned notions as participation, leadership or democracy. They experimented diverse approaches, methods and tools that allow to : bring together a collective ; involve people in social projects ; take decisions while respecting the difference ; share power and responsibilities, etc. The seminar was designed with the tradition of popular and non formal education : horizontality, non-jugment, focus on people's experience, alternance of theory and practice, etc. It allowed the participants to develop their skills and to be involved in knowledge building. Participants highlighted methods and tools that contribute to the success of group projects and allow groups to express their potential. They developed synthesis to keep track of their exchanges and to share the result of their meeting with others. The dissemination of their proposals should facilitate the emergence of collective projects providing social change in Europe. The seminar "From Singular to Plural" is finally a first stage in the creation of a network of exchange and expertise between the partners and should lead to the emergence of new cooperations in the future.