Child labor is a major threat to the health of children in the United States. The U.S. Department of Labor estimates that more than four million children are legally employed and that another one to two million are employed under illegal, often exploitative conditions. Across the United States, child labor accounts for 20,000 workers compensation claims, 200,000 injuries, thousands of cases of permanent disability, and more than 70 deaths each year. Agriculture and newspaper delivery are the two most hazardous areas of employment for children and adolescents. Poverty, massive immigration, and relaxation in enforcement of Federal child labor law are the three factors principally responsible for the last two decades' resurgence of child labor in the United States. Control of the hazards of child labor will require a combination of strategies including vigorous enforcement, education, and public health surveillance.