For years, diagnosis rates of Attention Deficit/Hyperactivity Disorder (ADHD) have continued to rise, presently making it one of the most commonly diagnosed neurodevelopmental disorders in American youth. Previous studies have examined how the cognitive deficits, impaired executive functions, and behavioral issues associated with ADHD negatively impact the academic performance of diagnosed adolescents. Past literature has also asserted that many racial-ethnic minority groups continue to be under-diagnosed with ADHD in comparison to their White peers, and those who are formally diagnosed often face significant barriers to care and treatment as a result of factors relating to their minority status. The inequality in ADHD diagnosis and treatment rates among youth has substantial implications for differences in the disorder’s impact on the academic performance of diverse racial-ethnic groups. Using the Fragile Families and Child Wellbeing Study (n = 2,566), I estimate a series of ordinary least squares regression models to examine race-ethnic differences in ADHD’s impact on academic performance on a standardized grade point average at age 15. My findings suggest that the negative relationship between ADHD diagnosis and G.P.A. is more pronounced among White adolescents compared to Black and Hispanic youth. Additionally, my findings indicate that potential mediator variables such as medication, special education service utilization, and grade retention do not substantially explain the differences in ADHD’s impact on G.P.A. The results presented in this paper imply that ADHD has a less clear impact on the grades of Black and Hispanic/Latino children than White children, potentially because youth of color face discrimination and structural inequality on the basis of their race/ethnicity that their White peers do not. Due to the negative impact of many complex factors associated with a racial-ethnic minority status, the effect of ADHD on minority children’s G.P.A.s may be less evident than on those of White youth, and instead more clearly linked to other variables such as household income or home environment.