Child maltreatment exemplifies a toxic relational environment that poses significant risks for maladaptation across biological and psychological domains of development. Research on child maltreatment can inform developmental theory, but more importantly, it can enhance the quality of clinical, legal, and policy-making decisions for maltreated children. This chapter addresses definitional, epidemiological, and etiological aspects of child maltreatment. A developmental psychopathology perspective is directed toward the discussion of the psychological and neurobiological sequelae of child maltreatment. Implications for prevention, intervention, and social policy are discussed, and recommendations for future research are proffered.