The economic valuation of biodiversity and ecosystem services has become a widespread tool to inform policy-makers about the consequences of environmental change. Assessments of environmental impacts at large geographic scales have led to growing policy and academic interest in transferring ecosystem service values from existing valuation studies to other ecosystem sites at a large geographic scale. This paper, published in Environmental and Resource Economics, proposes a methodology for scaling up ecosystem service values to estimate the welfare effects of ecosystem change at this larger geographic scale.