Both generic and environmental factors are likely to contribute to the pathogenesis of neurodevelopmental disorders. Even in heritable disorders of high penetrance, variability in timing of onset or severity of disease indicate a role for modifying principles. Investigation in animal models of the consequences of interactions between host response genes and microbes, toxins, and other environmental agents in a temporal context may elucidate the pathophysiology of a wide spectrum of chronic diseases. Here we review the evidence that infectious and immune factors may contribute to the pathogenesis of neurodevelopmental disorders, describe an animal model of neurodevelopmental disorders based upon viral infection, identify processes by which neural circuitry may be compromised, and outline plans for translational research in animal models and prospective human birth cohorts.