This article reviews causes of cognitive impairment in children with a focus on those in developing countries. The number of children with cognitive limitations is increasing, and for the majority there is little access to professional expertise. Causes include malnutrition, genetic diseases, infectious diseases such as meningitis, parasites, and cerebral malaria, in utero drug and alcohol exposure, newborn asphyxia, low birth weight, head injuries, and endocrine disorders. Many of these are preventable; however, resources for prevention are limited in most developing areas of the world. The challenge for this century is to encourage community leaders and government officials to take on the prevention of cognitive impairment as the highest priority for society. This article proposes that specialists in child behavior and development work with United Nations agencies to develop a "world cognitive impairment watch" to assess and assist each country annually in terms of risk factors, prevention programs, and early intervention programs.