While life in urban environments may confer a number of benefits, it may also result in a variety of exposures with toxic consequences for neurodevelopment and neuropsychological health. Neurotoxicants are any large number of chemicals or substances which interfere with normal function and/or compromise adaptation in the central and/or peripheral nervous system. Evidence suggests that neurotoxicant effects have a greater effect when occurring in utero and during early childhood. Recent findings exploring neural-level mechanisms provide a crucial opportunity to explore the ways in which environmental conditions may get “under the skin” to impact a number of psychological behaviors and cognitive processes; ultimately, allowing for greater synergy between macro- and micro-level efforts to improve mental health in the face of neurotoxicant exposures. In this review, we provide an overview of three types of neurotoxicants related to the built environment and relevant to brain development during childhood and adolescence: lead exposure, outdoor particulate matter pollution, and endocrine disrupting chemicals. We also discuss mechanisms through which these neurotoxicants impact central nervous system (CNS) function, including recent evidence from neuroimaging literature. Furthermore, we discuss neurotoxicants and mental health during development in the context of social determinants and how differences in the spatial distribution of neurotoxicant exposures result in health disparities which disproportionately impact low-income and minority populations. Multi-faceted approaches incorporating social systems and how they impact neurotoxicant exposures and downstream mental health will be key to reduce societal costs and improve quality of life for children, adolescents, and adults.