The goal of this project (one of three interrelated projects at the University of California-Davis Center for Children's Environmental Health (CCEH) is to determine if exposure to environmental toxicants early in development contributes to the etiology of neurodevelopmental disorders such as autism. A related goal is to determine whether susceptibility to autoimmune disease increases the neurotoxicity of environmental contaminants and increases the risk for developing disorders such as autism. The study will expose mouse strains with low or high susceptibility to autoimmunity perinatally to either methylmercury, polychlorinated biphenyl 95, or polybrominated diphenyl ether 47. The effects of toxicant exposure between these mouse strains on brain development, complex social behaviors, and immune system function will then be compared. Understanding how exposure to environmental toxicants may contribute to the etiology of neurodevelopmental disorders is important so that the exposure risks can be identified and minimized.