This paper explores the Lay Theories of ADHD of stakeholders (teacher, parent and student) in an Irish context. Academic theories of difference have and continue to evolve, moving from medicalisation, through more socially oriented ideas, to more current trend around neurodivergence. However, inclusion as a process is socially negotiated within classrooms and the wider community. An understanding of stakeholders' lay theories or their beliefs about ADHD (e.g., what causes it and how to respond) gives us insights into this process. This paper draws on findings from a multi-case study (N = 15) that explored the lay theories of 17 parents, 15 students (7-18 year; Mean = 12.8; SD = 3.09), and 12 teachers (4 primary and 8 secondary) affected by ADHD in mainstream schools. Participants took part in a semi-structured interview. A data-driven Thematic Analysis identified three themes: what is ADHD, do they have control, and medication. Each stakeholder group held distinctly different views, which created considerable confusion. Findings are discussed in terms the need for the education of key stakeholders, and what those educational initiatives might include, as well as for the role of collaboration within the process of inclusion.