A decision rationale for ocean disposal based on a predictive hazard assessment research stragtegy is presented. The conceptual framework for hazard assessment is outlined, and its major components are identified and discussed. The strategy involves the synthesis of results from separate exposure and effects components in order to provide a scientific basis for estimating the probability (risk) of harm to the aquatic environment. The exposure assessment component consists of methodologies for determining biological effects as a function of contaminant exposure concentrations. Two case studies illustrate how a hazard assessment strategy synthesizes exposure and effects information to provide a casual linkage between mass inputs of contaminants and biological effects. The first study examines sewage-sludge disposal atDeep-water Dumpsite-106. The second study, which examines the disposal of dredged material in a shallow coastal site in central Long Island Sound, is a field verification program designed to test methodologies required for the acquisition of exposure and effects information. Both the laboratory and field data are synthesized to evaluate the accuracy and confidence of predictions of the individual methods, the tiered hierarchal concept, and the final prediction.