This article presents a new approach to developing proper strategies for multicriteria medium- and long-term power generation expansion planning. The desired strategies present a predetermined number of appropriate planning alternatives, which should be selected from a vast initial set in accordance with the given multiple criteria. These multiple criteria, caused by considering environmental criteria (such as SO2, NOx, and particulate emissions minimization) together with economic and other criteria, make multicriteria analysis a cornerstone of the proposed approach. The proposed multicriteria analysis includes determining a criteria assessment vector for each initial alternative and multicriteria optimization of a set of such initial criteria assessment vectors. The basic issue of this article is to reflect development of calculation models for the environmental criteria (to create the criteria assessment vectors) together with appropriate environmental investigations. Suitable solution methodology and software, applied to the conditions prevailing in Israel, have been developed for the proposed approach.