Understanding global environmental change and predicting the consequences of global environmental variability are becoming increasingly important to the nations of the world. Global change is now on the agenda of world leaders, a substantial number of whom are deeply concerned with the potential economic, social and political consequences of human-induced variabilities in the climate system and other aspects of global environmental change. Uncertainty of scientific knowledge of global and regional processes and the limited ability of science to predict the behavior of the Earth system are of major concern. These realities place upon the international scientific community a responsibili­ ty to expand scientific knowledge and predictive capabilities about the fundamental processes that control the Earth system. The response of the scientific community has been phenomenal. National and international planning and coordination mechanisms have been established to address the fundamental scientific questions of global environmental change, e.g., the International Geosphere-Biosphere Programme, the World Climate Research Programme, and the U.S. Global Change Research Program and other such national programs. This NATO Workshop, entitled ''The Science of Global Environmental Change," focused on the state of knowledge in global change science and on assisting the Scientific Affairs Division of NATO in designing a 5-year program of Advanced Research Workshops (ARWs) and Advanced Study Institutes (ASIs) in the area of global change that would make a meaningful contribution to the international activities already underway.