Energy communities in Denmark, Italy, and Norway were investigated to explore factors that enable or hinder the behavioral and social transformations necessary to achieve a socially just environmental transition, particularly in projects involving vulnerable individuals. This study seeks to understand how energy communities drive behavioral change and social transformation by examining seven energy communities in Denmark, Italy, and Norway. Consequently, 57 semi-structured interviews were conducted among the seven cases. This paper suggests fostering behavioral shifts towards energy-saving practices in Norway and Denmark to reduce energy consumption and mitigate energy vulnerability. Education and awareness-raising on energy-saving measures in Italy have already led to tangible changes in daily behaviors among vulnerable groups. Across all countries, prior environmental attitudes, trust in project leaders and project plans, and community support were crucial in driving participation and behavioral change. Additionally, financial incentives motivated some participants, especially those from vulnerable groups facing high living costs. Key enablers of change included access to knowledge and a sense of community, while barriers like financial constraints and time limitations hindered broader participation. The study highlights the importance of involving vulnerable individuals in decision-making to enhance their sense of ownership and commitment to energy-saving practices. For sustainable behavioral change, it is essential to address environmental motivations and the financial, political, social, and practical considerations that affect vulnerable populations’ decision to join energy communities.