Over the past several decades, a body of research has emerged on how cognitive competencies and their underlying neurobiological substrates change with development. This research exemplifies a dimensional approach of how cognitive abilities gradually evolve from simple to complex, how they vary across individuals, and how such variation contributes to risk for or resilience from mental disorders. Using dimensional measures to capture developmental and individual variation in cognition rather than relying on categorical or diagnostic measures may enhance our ability to delineate brainbehavior associations and link them more directly to core elements of psychopathology (1). This issue of Biological Psychiatry includes two articles that use meta-analyses to report on the effects of stimulants on dimensional measures of cognition and brain function in children and adolescents with attention-deficit/ hyperactivity disorder (ADHD) (2,3). These studies emphasize how disruption in the organization of prefrontal circuitry may lead to changes in cognition and symptoms of ADHD and the therapeutic role for stimulants in targeting these cognitive impairments.