The collaboration between the two Shores of the Mediterranean Sea established within WP4, coordinated by ENEA, Italy, aimed at the harmonization of the legislative and regulatory framework on energy efficiency (EE) and renewable energy sources (RES), for contributing to the creation of a common energy market. The three deliverables elaborated by project partners provide inputs for policy makers and stakeholders to accomplish sustainable energy systems at Mediterranean Regional level. In particular, the basic elements to elaborate a joint proposal have been highlighted in the following studies, taking into account that developing a sustainable energy system requires enacting wide-ranging public policies: an accurate coordination with industrial and research policies is needed, having awareness of the existing tight connections between energy and environmental policies and economic competitiveness. National energy plans and programmes should help unlock private investment flow, also putting in place innovative financing mechanisms.