The organic matter preserved in estuarine sediments provides a number of useful indicators, or ‘‘proxies,’’that can be used to infer paleoenvironmental changes. One type of paleoenvironmental change is anthropogenic eutrophication. Following the operational definition of eutrophication by Nixon (1995a), we define anthropogenic eutrophication as ‘‘an increase in the rate of supply of organic matter to an ecosystem that is caused by human activities.’’The human activity largely responsible for increasing the rate of supply of organic matter in temperate estuaries has been the increased loading of nitrogen (Nixon, 1995a; Vitousek, et al., 1997). Nixon et al.(Chapter 5) and Hamburg et al.(Chapter 6), both in this volume, focus on historical nitrogen inputs from the human landscape, particularly from sewage treatment facilities and agriculture. In this study, we utilize several proxy measurements to analyze the organic matter from radiometrically dated (137Cs, 210Pb, 14C) sediment cores from three sites in the Narragansett Bay ecosystem for evidence of anthropogenic eutrophication.