Children from socioeconomically disadvantaged families are at risk for malnutrition, learning disabilities, and many other problems associated with poverty. Increasing application of event-related potentials (ERP) methods has been made in studies of aberrant development, although little systematic effort has been devoted to assess the relationship of socioeconomic factors and ERP measures. In the present study, late positive ERPs, age, intelligence and other demographic variables were assessed in a group of 49 disadvantaged children aged six to twelve years. The Stanford-Binet full-scale was used to index child IQ and the Ammons Quick Test was used for maternal IQ. Quality of the home caregiving environment was evaluated during a home visit using the Caldwell Home inventory. Socioeconomic status (SES) was measured with the Hollingshead two-factor index. ERPs were recorded at Fz, Cz and Pz during an auditory signal detection task. The amplitude and latency of a late positive component (LPC) peaking 300-600 msec after stimulus onset were measured. The results indicated marked changes in LPC latency during childhood, but only isolated relationships among LPC measures, child IQ and other demographic variables. Whether or not ERPs provide 'culture free' measures of cognitive development is a question that requires further study. LPC amplitude also varied with increasing blood lead levels, observed five years earlier, suggesting a possible association of attention-deficit disorder and lead absorption in early childhood.