Parent and teacher reports of symptoms of Attention Deficit Hyperactivity Disorder (ADHD) in children often differ from each other. These informant report differences may occur in systematic ways that vary by child socioeconomic status (SES) and race, but little is known about how SES and race together relate to parent and teacher report of ADHD symptoms in school-aged children. We examined the relationship between child SES, child race and parent and teacher reports of ADHD symptoms in two samples of school-aged Caucasian and African American children being evaluated for ADHD (N = 1056; N = 317). Multivariate regression was used to predict parent and teacher reports of ADHD symptoms from child SES, race, age, gender and interaction terms. The Wald test of parameter constraints was used to test the contrast between the predictors of interest and parent and teacher report of symptoms. In the second sample, we also examined observer report measures of ADHD symptoms during one-to-one testing and in the classroom. In both samples, lower SES was associated with higher levels of inattention symptoms, as reported by teachers, but not by parents. Lower SES was also associated with higher levels of hyperactivity/impulsivity symptoms, as reported by both teachers and parents. African American race was associated with higher levels of inattention and hyperactivity/impulsivity symptoms reported by teachers than reported by parents. Observer report measures showed a different pattern of associations with SES and race. Investigating how children’s SES and race influence cross-informant agreement on ratings of children’s behavior might lead to the development of better assessment practices and more accurate diagnoses for diverse child populations.