Streambed sediment and fish tissue were collected at 14 river sites in eastern New England during low-flow conditions in 1998 and 1999 as part of the New England Coastal Basins (NECB) study of the U.S. Geological Survey National Water-Quality Assessment (NAWQA) Program. Sampling sites were selected over a range of urban settings. Population densities at selected sites ranged from 26 to 3,585 people per square mile, and urban land use ranged from 1 to 68 percent. The streambed sediment samples were analyzed for a total of 141 contaminants, including 45 trace elements, 32 organochlorine compounds, and 64 semi-volatile organic compounds. The fish tissue samples were analyzed for 22 trace elements and 28 organochlorine compounds. Concentrations of selected contaminants in both streambed sediment and fish tissue correlated more strongly with population density than with other watershed characteristics. Cadmium, copper, lead, mercury, zinc, total polycyclic aromatic hydrocarbons (PAHs), total polychlorinated biphenyls (PCBs), dichloro diphenyl trichloroethane and metabolites (DDTM), and total chlordane in streambed sediment all showed strong positive correlations with population density (rho = 0.71 to 0.85, p value = 0.005 to