In January, 1998, the Alfred P. Sloan Foundation and the Office of Naval Research sponsored a workshop organized by the Ocean Studies Board of the National Research Council 1, which brought together ecologists, oceanographers, fisheries scientists, and modelers to discuss the value, timeliness, and feasibility of assessing the global distribution and abundance of marine life, with emphasis on higher trophic levels. A global assessment of marine life would aid in predicting the causes of ecosystem change and resulting consequences to fisheries, trophic structure, and dynamics of marine systems. The workshop identified 3 goals: to determine the biomass of marine biota, especially the higher trophic levels; to determine how this biomass is distributed spatially and by size and taxon and; to investigate how these distributions are maintained or changed. Significant advances toward these ambitious goals were considered possible on a 10-year time frame using an iterative process of modeling and observation which estimated global abundance through understanding of the trophic structure, population sizes, and flow of matter through the food webs of major biogeographic zones in the ocean. A pilot observation program would focus on areas of greatest uncertainty identified to be the abundances, distributions and rates of trophic transfer of poorly known open ocean animals, primarily cephalopods, mesopelagic animals, macrocrustaceans, gelatinous zooplankton, epipelagic fish and small cetaceans. Assessment of open ocean taxa requires significant technological development, including acoustical, optical, genetic, and chemical approaches. A global assessment program based on atrophic dynamics/modeling approach presented the prospect of significant scientific and societal benefits but would require the mobilization of a multiagency and multinational effort.