The Millennium Ecosystem Assessment argued that biodiversity loss matters because it compromises the 'ecosystem services' on which human life depends at many different scales. The international biodiversity research program, Diversitas, explores the science behind the linkages between biodiversity, ecosystem services, and human well-being. BESTNet will bring the insights from this work to young researchers in the US through two research-training activities. First, research training workshops will address topics under discussion in Diversitas, including the valuation of ecosystem services, health and biodiversity loss, biodiversity information and community-based use of natural resources, and biodiversity in agricultural landscapes. Second, doctoral students will be funded to spend time in the labs of participating scientists in the US and abroad. BESTNet will also make a wider contribution to the development of sustainability science and policy. It will (a) develop an interdisciplinary community committed to policy-relevant research into the links between biodiversity change and human activities; (b) enhance the capacity to undertake interdisciplinary research within existing life and social science departments in US universities; (c) synthesize research results on the local consequences of international biodiversity change; and (d) disseminate these results to decision-makers. In addition, it is expected that the network will substantially strengthen US scientific input into the global-change programs and other international initiatives.