The creation of the Energy Community in 2006 and its work since then emphasize the strategic importance of the energy sector for the development of South-Eastern European countries, from the perspectives of the European Commission, European Union (EU) member states, and the Energy Community’s contracting parties. Energy efficiency is a key area within the energy sector which is recognized by the Energy Community and its contracting parties continuously and increasingly. Corresponding to the needs and personal efforts of the South-Eastern European countries to achieve progress in the area of energy efficiency, more and more donor organizations and international financial institutions have also offered their support in form of technical and financial assistance. This kind of international cooperation has produced already successful results, in both, concrete projects implementation, as well as through strengthened capacities in the partner countries, to deal with energy efficiency. However, as “energy” is a challenging sector for the EU member states, it is more so a challenge for the member countries of the Energy Community, which are often also struggling with fundamental transitional issues.