The low carbon energy transition is an important target of the EU. The role citizens can play in the transition process is critical. Social innovation can boost citizens’ participation. In addition, collective action initiatives (CAIs) encourage citizens’ mobilization and ensure the public’s contribution in the transition process. However, there is a lack of understanding of CAI development as well as in estimating its entire potentiality. The EU-funded COMETS project will investigate CAI evolution and contribution in the energy transition efforts at EU and national level in six countries. COMETS aims to enrich our scientific understanding of the incentives and aspirations of CAIs, its limitations, as well as its historical and future performance in the energy transition.