In recent decades, the socio-economic implications of environmental change have made themselves clearer and clearer. Rapidly degrading ecosystems all over the world have resulted in people competing for increasingly scarce natural resources, companies facing unplanned higher production costs and therefore lower proits due to ecosystem changes, and governments having to invest in infrastructure to replace services that used to be provided by the environment for free. As a first source of information regarding development projects, environmental and social impact assessment (ESIA) needs to relect the linkages between environmental change and socio-economic achievements. It needs to demonstrate not only how the project might impact the environment and what the socio-economic implications of these impacts could be; in a context of degrading ecosystems and ever more scarce natural resources, ESIA also needs to inform developers about how project performance could be affected by environmental change driven by third-party activities such as farmers diverting water upstream from the project. Despite a number of initiatives to promote integrated impact assessment (Brownlie 2005, Slootweg et al. 2001), ESIA still typically assesses different biophysical elements (e.g., air, water, land, fauna and lora/ biodiversity) and socio-economic elements (e.g., demography, health, culture, and livelihoods) separately. However, new regulatory and inancial impact assessment standards require that ESIA systematically addresses impacts on ecosystem services, which by deinition link people and their environment (Box 1). Addressing ecosystem services in ESIA acknowledges that some biophysical aspects are socio-economically important and calls for an integrated approach across biophysical and socio-economic disciplines.