The United Nations Development Programme (UNDP) and the United Nations Environment Programme (UNEP) organized this international symposium to: • Seek consensus on priority environmental assessment and sustainable development issues and the core data sets needed to respond to these issues; • Define the minimum characteristics of these data in relation to national and transnational purposes; • Establish collaborative mechanisms to foster the harmonization of core environmental data; and • Examine the bathers to general access and use of these data.