Attention-deficit/hyperactivity disorder (ADHD) has been associated with poor academic performance, but little is known about learning trajectories and risk factors for poor academic outcomes. This study investigates the relationship between ADHD and academic performance in students with ADHD ( n = 87), students with subclinical ADHD ( n = 23), and matched comparisons ( n = 112), accounting for exceptional student education (ESE) status. Academic outcomes included reading and math scores on a state-mandated achievement test, the Florida Comprehensive Assessment Test (FCAT), grade point averages, retention, and graduation. Cross-sectional and longitudinal analyses were conducted, adjusting for sociodemographic characteristics and ESE, to test ADHD status as an independent outcome predictor. Students with ADHD received more special education services (53%) than subclinical (26%) and comparison (10%) students ( p < .01). ADHD was associated with poorer academic performance on all outcome measures, but only when ESE status was not accounted for. In the longitudinal analysis students with ADHD and special education needs consistently achieved lower FCAT scores than peers in the comparison group but showed comparable learning gains, or slopes, over time. Students without special education needs and gifted students with ADHD had comparable achievement and learning gains as comparison students of the same ESE status. Results suggest that special education status is a driving factor in underachievement among students with ADHD.