The acute respiratory distress syndrome (ARDS), a process of non-hydrostatic pulmonary edema and hypoxemia associated with a variety of etiologies carries a high morbidity, mortality (10–90%) and financial cost. The reported annual incidence in the United States is 150000 cases, but this figure has been challenged and may be different in Europe. Part of the reason for these uncertainties is the heterogeneity of diseases underlying ARDS and the lack of uniform definitions for ARDS. Thus, those whose wish to know the true incidence and outcome on this clinical syndrome are stymied. The European American Consensus Committee on ARDS was formed to focus on these issues and on the pathophysiologic mechanisms of the process. It was felt that international coordination between North America and Europe in clinical studies of ARDS was becoming increasingly important in order to address the recent plethora of potential therapeutic agents for the prevention and treatment of ARDS.