Lead neurotoxicity is considered a problem in young children and the long-term effects of lead exposure on them have yet to be determined. Studies have been completed to determine how lead exposure has affected children through their most important developmental stages. However, there is a lack of research to uncover any long-term effects lead may have as children enter adulthood. The purpose of this study was to determine long-term effects of lead exposure on IQ. The theoretical foundation for this study is the Cattell Horn Carroll theory of intelligence, which is based on fluid (novel experiences) and crystallized (previous experiences) intelligence. This study focused on individuals who were exposed to lead as children and are now young adults (ages 18-25). These individuals were part of a class action lawsuit and referred to a clinical psychologist from a private clinic who conducted IQ testing. In this non-experimental quantitative study, a multiple regression analysis was conducted on secondary data. Independent variables were first and last blood lead and Appearance, Pulse, Grimace, Activity, and Respiration scores as indicated from medical records. The dependent variables were the perceptual reasoning index, and verbal comprehension index of the WAIS-IV administered by a licensed clinical psychologist. The results of this study showed that childhood lead toxicity did not predict IQ scores in young adulthood. More research needs to be completed so that governmental agencies will have more information to be proactive in creating and changing policies around the use of lead in products that people use daily. This could lead to positive social change by placing an emphasis on early identification and treatment of lead exposure.