The authors show an application of the multicriteria decision-making methodology used to assess an action plan for the diffusion of renewable energy technologies at regional scale. This methodological tool gives the decision-maker considerable help in the selection of the most suitable innovative technologies in the energy sector, according to preliminary fixed objectives. In this paper, a case study is carried out for the island of Sardinia. This region presents, on one hand, a high potential for energy resources exploitation, but on the other hand, it represents a specific case among other Italian regions, because of its socio-economic status and history. Three decision scenarios have been supposed, each one representing a coherent set of actions, on the basis of which strategies of diffusion are developed.