Actionable strategies for navigating Cuba's energy transition are presented in this volume, which contains 18 rigorously peer-reviewed papers selected from over 120 presentations at the II International Conference on Renewable Energy Sources, Energy Efficiency, and the Environment (Havana, 2025). These contributions take a distinctly practical approach—connecting technological innovations in renewable generation and energy efficiency with actionable frameworks for environmental protection and circular economy models. What distinguishes this collection is its grounding in local context enriched by international collaboration. The scope spans technical advances in energy systems alongside economic strategies for sustainable competitiveness, making this volume valuable for energy specialists seeking implementable methodologies, environmental policymakers requiring evidence-based guidance, and business leaders exploring opportunities within Cuba's evolving energy landscape. It serves as both a record of current research and a practical tool for stakeholders committed to building a more resilient and self-sufficient energy future.