Attention-deficit/hyperactivity disorder (ADHD) overdiagnosis and overtreatment unnecessarily exposes children to potential harm and contributes to provider and community skepticism toward those with moderate or severe symptoms and significant impairments, resulting in less supportive care. Yet, which sociodemographic groups of children are overdiagnosed and overtreated for ADHD is poorly understood. We conducted descriptive and logistic regression analyses of a population-based subsample of 1,070 U.S. elementary schoolchildren who had displayed above-average levels of independently assessed behavioral, academic, or executive functioning the year prior to their initial ADHD diagnoses and who did not have prior diagnostic histories. Among these children, (a) 27% of White children versus 19% of non-White children were later diagnosed with ADHD and (b) 20% of White children versus 14% of non-White children were later using medication. In adjusted analyses, White children are more likely to later be diagnosed (odds ratio [OR] range = 1.70-2.62) and using medication (OR range = 1.70-2.37) among those whose prior behavioral, academic, and executive functioning suggested that they were unlikely to have ADHD.