Psychostimulants are first-line pharmacological treatments for attention deficit hyperactivity disorder (ADHD), although symptom reduction varies widely between patients and these individual differences in treatment response are poorly understood. The authors sought to examine whether the resting-state functional connectivity within and between cingulo-opercular, striato-thalamic, and default mode networks was associated with treatment response to psychostimulant medication, and whether this relationship changed with development.