Child labor, the penultimate form of cheap labor, is endemic in poor countries; it also occurs in affluent countries. Little information has been available on injuries, disease, and effects on growth and development in the tens of millions of children at risk. Preventive and control measures are eliminating the gross abuses, tracing and banning hazardous exposures to toxic agents, eliminating risks of injuries and ergonomic strain, providing health services for working children through the primary health care network, and developing international failsafe design standards for tools and work systems, if these children must work. There is a need to train public health professionals, pediatricians, and maternal and child health care personnel in carrying out simple descriptive epidemiologic studies and setting up interventive programs. Eliminating the worst conditions and controlling hazards where there is no imminent alternative to child labor are suggested as the basis for a two-pronged strategy for protecting children who are forced to work.