With recent evidence that the vast majority of mental disorders, even when they emerge in adulthood, are caused by abnormal neurodevelopment and resultant emphasis on prevention and early intervention, there is a need to put developmental neuropsychopharmacology at the top of the agenda in mental health research. The target of drug discovery should shift toward a population younger than the one that is typically included in clinical trials. Developmental therapeutic windows have not been sufficiently factored into the design of trials of psychotropic drugs for mental disorders. We should devote more research to identifying the developmental stages at which individuals are most likely to respond to particular treatments. This is not only a matter of trying to replicate what has been found in individuals with mature brains; it is about searching for new strategies that address developing brains while the therapeutic window for their effect is still open. The future of research in this area should focus on the use of drugs for primary and secondary prevention that would modify abnormal brain development and drugs that are neuroprotective and serve to protect the brain from environmental stressors.