Workers around the world-despite vast differences in their physical, social, economic, and political environments-facevirtually the same kinds of workplace hazards. These hazards are traditionally categorized into four broad types: chemical,biological, physical, and psychosocial. What emerges from our incomplete knowledge of their risk, however, is that the morethan 80 percent of the world's workforce that resides in the developing world disproportionately shares in the global burdenof occupational disease and injury. Several classic occupational diseases, such as silicosis and lead poisoning, that have beensubstantially eliminated in industrial countries remain endemic elsewhere in the world. Whether this high and preventableburden of ill health faced by workers in the developing world is the result of ignorance, inattention, or intent, compellingevidence indicates that work-related health conditions could be substantially reduced, often at modest cost.