Developmental psychopathology is described as a conceptual approach that involves a set of research methods that capitalize on developmental and psychopathological variations to ask questions about mechanisms and processes. Achievements are described in relation to attachment and attachment disorders, autism, schizophrenia, childhood antecedents of adult psychopathology, testing for environmental mediation of risk effects, gene-environment interplay, intellectual and language functioning, effects of mentally ill parents on the children, stress and vulnerability to depression, ethnicity and schizophrenia, and drug response. Continuities and discontinuities over the course of development are discussed in relation to attention-deficit/hyperactivity disorder, antisocial behavior, eating disorders, substance abuse and dependency, pharmacological and behavioral addictions, and a range of other disorders. Research challenges are considered in relation to spectrum concepts, the adolescent development of a female preponderance for depression, the mechanisms involved in age differences in response to drugs and to lateralized brain injury, the processing of experiences, the biological embedding of experiences, individual differences in response to environmental hazards, nature-nurture integration, and brain plasticity.