Pesticide residues can be detected in the tissues of every human because of their world-wide distribution and chemical properties. Despite many thousands of scientific publications on pesticide mechanisms of action, however, surprisingly little is known of their potential as a source of developmental disabilities resulting from interference with brain development. The lack of information is particularly surprising because the most popular classes of insecticides are designed specifically as neurotoxicants. Two broad classes are reviewed here: the organophosphates and the organochlorine compounds. The evidence for developmental neurotoxicity arising from organophosphate exposure is ambiguous, but careful animal studies and residual effects in humans following acute intoxication suggest that these compounds may prove hazardous to the developing brain at exposure levels below those inducing overt signs. The organochlorine compounds provide firmer evidence of developmental neurotoxicity in humans. Phenomena such as chemically induced kindling have been observed in animals and persistent deficits have been reported in children after acute poisoning. Given the many poisoning episodes in children reported every year, and compulsive application to nearly every species of flora on the planet, the scope of the problem is inconsistent with the remarkably sparse information available.