<p>Racial disparities in ADHD diagnoses may be attributable to parent-teacher discrepancies in symptom ratings, as teachers rate Black children as more symptomatic than non-Black children. Implicit racial biases may be a contributor to these parent-teacher differences. This study examined specific forms of racial biases among White teachers and Black parents, and their association with ratings of Black and White children’s ADHD behaviors. Participants watched short videoclips and rated children’s ADHD symptoms, and completed measures of implicit and explicit racial attitudes and ADHD stereotypes. Results showed that White teachers demonstrated more implicit biases than did Black parents. Implicit racial attitudes toward Black boys were associated with biased ratings of Black boys’ ADHD symptoms, and explicit racial attitudes were associated with biased ratings of Black girls’ ADHD symptoms. These findings demonstrate a potential role of teachers’ implicit racial biases in ratings of Black children’s externalizing behaviors, including ADHD.</p>