The knowledge and attitudes of practicing teachers regarding ADHD were compared with those of undergraduate education students. Key elements of studies of American and Canadian teachers by Jerome, Gordon, and Hustler (1994) and Jerome, Washington, Laine, and Segal (1999) were replicated. Information was gathered about participants' demographic background (training in ADHD), attitudes towards ADHD, and knowledge about its diagnosis and treatment. Results confirmed the existence of some knowledge gaps, although both practicing teachers and undergraduate education students possessed sound information about ADHD. Misconceptions about ADHD primarily concerned dietary treatment. Attitudes and knowledge were significantly correlated and most participants regarded ADHD as a valid diagnosis with implications for the school setting, and expressed a desire for comprehensive training. Despite similar results for both samples, teachers achieved higher accuracy on knowledge-based questions. These results are discrepant from those of Jerome et al. (1999) who found teachers and students to be similar in factual knowledge. Implications of these findings for curriculum development in academia and in-service teacher training are highlighted. (Contains 5 tables.)