The purpose of this study is to assess the economic and social effects of projected geothermal resource development for both direct use and electric power generation and to analyze local regulatory policy options designed to mitigate adverse effects. The key issues are land use, fiscal and public infrastructure systems, demography, and the local economy. The study has seven elements: a computer-based inventory and analysis of land characteristics, constraints, sensitivity, and suitability for various land uses; projections of direct and electric geothermal development; primary and induced economic activity using an input-output model; demographic changes; the land and infrastructural demand created; an assessment of the economic and social effects of various configurations in land use that could result; and an analysis of various local regulatory policy options to mitigate adverse effects. The study is a cooperative effort among two national laboratories, a regional agency, and the four Geysers-area counties (Lake, Mendocino, Napa, and Sonoma). The assessment results are intended to guide Department of Energy planners on the environmental consequences of program implementation. The regulatory policy analysis is intended for local officials who are implementing development-management policy.