The present study examined the genetic and environmental mediation of the well-established relationship between childhood maltreatment and children’s conduct problems. It is one of few studies to address this question using the bivariate behavior genetic method, which has been shown to provide a valid test of environmental mediation (Purcell and Koenen 2005). It examined a genetically informative subsample of the National Longitudinal Study of Adolescent Health, a large, longitudinal study of adolescent health and behavior.