Objective: To identify factors associated with discrepancy in parent–teacher reporting of symptoms of ADHD. Method: Parents and teachers rated 1,364 children using an ADHD rating scale. Data were analyzed using multiple regressions and ANOVA. Results: Demographic variables predicted greater parent–teacher discrepancy for ethnic minority families than for Caucasian families. Comorbidity variables predicted greater discrepancy for children who had a comorbid externalizing disorder. Academic performance variables predicted discrepancy for children who showed more homework problems. When all significant predictors were entered together, externalizing disorders and homework problems emerged as significant predictors. Participants whose parents reported higher levels of symptoms were of significantly higher socioeconomic status. Participants whose teachers reported higher levels of symptoms were significantly less likely to have a comorbid externalizing disorder and parent-reported homework problems. Conclusion: Parent–teacher discrepancies are likely to occur when the child has significant homework and externalizing behavior problems.