This article presents findings from a mixed methods study which explored the perspectives and experiences of post-primary teachers in Ireland regarding students with Attention Deficit Hyperactivity Disorder (ADHD). Using an anonymous online questionnaire (n = 239) and semi-structured interviews (n = 8), this research examined teachers' views and opinions of ADHD, its impact in the classroom and their experiences with diagnosed students. Teachers reported that students with ADHD presented numerous challenges in the classroom which had a negative impact on teaching and learning, and they felt professionally ill-equipped to properly support their students. We argue there are multiple tensions and contradictions at play within the Irish educational system which may be impacting both teachers' perspectives of students with ADHD and the inclusion of these students in the larger post-primary context.