The National Estuarine Research Reserve System (NERRS) consists of an integrated network of 27 reserve sites in 19 biogeographical subregions. These estuarine reserves are protected sites where comprehensive databases are compiled to characterize the natural and anthropogenic processes governing ecosystem stability and change. Data collected by research and monitoring programs of the NERRS provide the foundation for sound coastal management decision-making. Three principal areas of research and monitoring are targeted by the NERRS: (1) abiotic factors, including meteorological, water quality, and physical conditions; (2) biotic features, including both flora and fauna; and (3) land use and habitat change characterizations. Baseline conditions and trends in physical, chemical, and biological parameters are vital for evaluating changes that occur in response to various environmental stressors and long-term climate change throughout the network of estuarine ecosystems. The NERRS is a particularly effective program because its research and monitoring activities occur in all geographical regions of the United States and almost every recognized climatic zone. Because of the geographic expanse of the NERRS and its intensive and extensive research and monitoring initiatives, an ideal platform exists to characterize both the short-term variability and long-term changes in estuarine systems nationwide and to make these results available to support informed decision-making and increased public awareness of coastal systems.