This paper provides novel additional evidence on the characteristics of Collective Action Initiatives (CAIs), investigating their role within the European energy sector. It analyses and presents results of a survey administered in six European countries: the Netherlands, Belgium, Italy, Poland, Estonia, and Spain. CAIs are studied in light of four key dimensions, those being their creation dynamics, the way they are organized, financed, and the activities they undertake. The results presented are also interpreted to reflect on their role as drivers of social innovation (SI) within energy transition in Europe. The analysis shows that the contribution of CAIs to the energy transition has a much wider scope than the development of energy projects and provision of energy services. CAIs are intrinsically socially innovative models of implementation as characterised by a strong level of citizen involvement and participation. Moreover, they have a potential multi-level role in the energy transition, from the technological and social perspectives. Indeed, alongside traditional energy activities, our results show that CAIs are evolving and expanding towards socially innovative activities, raising awareness on environmental issues, promoting citizens’ mobilization, and fostering social inclusion.