A teacher's intention to refer students to mental health professionals is important to the early identification of attention-deficit/hyperactivity disorder (ADHD) and prevention of further problems. The theory of planned behavior (TPB) was used to determine the strongest belief-related predictors of a teacher's intentions to refer students with ADHD symptoms to a mental health professional in the U.S. and South Korea. Perceived stigma and knowledge of ADHD were additional predictors in examining the role of culture in a teacher's perceptions of the public's stigma toward ADHD and a teachers' knowledge of ADHD. Cross-cultural differences exist. U.S. teachers' (n = 235) intentions to refer were predicted by all TPB variables (i.e., attitudes about referral, beliefs about whether important others would approve of making a referral, and perceived behavioral control in making a referral). However, among South Korean teachers (n = 144), behavioral control and perceived stigma were the only predictors. The results imply the importance of considering the cultural context in understanding a teacher's referral behaviors.