This volume presents the proceedings of a symposium on the Environmental Monitoring and Assessment Program (EMAP), held in Albany, NY, USA, in April, 1997. A research programme of the US Environmental Protection Agency, EMAP has been advancing the state of the science in ecological indicator development, statistical sampling design, landscape characterization, and other tools of environmental monitoring since the programme's inception in the late 1980s. EMAP's goal is to develop and demonstrate the science necessary to monitor status and trends in the condition of ecological resources at multiple spatial and temporal scales. These proceedings feature recent research on ecological indicators, and results from seven years of EMAP monitoring in estuarine, forest, and freshwater ecosystems.