A sampling strategy designed around contaminant source (agricultural runoff, direct discharge) and fate (solubles, particulates, sediments) and the hydrodynamics of the system studied is required to characterize the exposure of estuarine biota to contaminants. Field data obtained on contaminant effects should be applicable to risk assessment in order to verify approaches to predicting contaminant fate and effects in estuarine systems. Only through systematic evaluations of field and laboratory exposure-response relationships will we be able to quantify the limits of applicability of laboratory data used for ecological risk assessment. Survival of caged test animals at field test sites provides data for direct comparison with laboratory toxicity test results. Coupling survival and other effects data from caged animal studies with assessments of stocks and dynamics of populations of the same or a related species at the field site may allow extrapolation from simple laboratory and field test results (acute or chronic) to more complex and ecologically significant endpoints. This paper presents examples of various approaches to contaminant problems in estuaries and discusses their applications to risk assessment procedures.