Many children adapt to life after trauma, but children with ADHD may be at risk for post-traumatic maladaptation. ADHD is often comorbid with mental health disorders and deficits in cognitive functioning. Using data from the Multimodal Treatment of Children with ADHD study, a randomized clinical trial that tested treatments for ADHD in 579 children and later recruited 289 comparison children, the present study tests whether trauma predicts more severe levels and faster increases in depression and anxiety for children with ADHD versus developmentally typical peers. Interpersonal trauma predicted elevated depression and anxiety symptom severity, but not trajectories. Natural trauma predicted elevated anxiety symptoms, but not trajectories. Last, ADHD diagnosis predicted elevated depression symptoms, but not trajectories. There were no trauma x ADHD interactions on symptom levels or trajectories. This study informs practice and policy by guiding practitioners to use trauma history to identify children who demonstrate persistent internalizing symptoms.