There is a substantial body of research to indicate the potential wider benefits of sustained, effective musical activity on children's intellectual, social and emotional development, including children with special needs. However, there is limited research evidence concerning music education and young people diagnosed with Attention Deficit Hyperactivity Disorder (ADHD), whose symptoms can negatively affect behaviour and development at both home and school. Accordingly, following an exploratory pilot action case study, the intention of this multiple case study approach was to investigate how and to what extent ADHD behaviour is evidenced in a music education context. The methodology of the main study included structured observations in three different case studies, including between- and within-case contrasting settings. Real-time observational data were gathered overall several weeks, supported by video, and subjected to analysis and synthesis in terms of both musical behaviours and development and ADHD profiles. Observational contexts embraced small group music-making, one-to-one studio-based lessons, group instrumental lessons and orchestra rehearsals of Primary and Secondary school-aged pupils with a formal assessment of ADHD across several school terms. Overall, the three core attributes of ADHD (inattention, hyperactivity and impulsivity) were evidenced at different moments during the case study music education programmes. However, data analyses suggest that ADHD symptoms can be less entirely absent in the actual musical acts of playing and performing. Furthermore, analyses of the data suggest that the perception of ADHD in music is likely to be related to the pedagogical approach and the way that the educational experience is set up. In particular, the evidence suggests that an effective and inclusive musical strategy can integrate ADHD behaviour into successful individual and collective music making. Conversely, negative attitudes towards ADHD behaviour can hinder teachers' effective practices and enhance an adverse perception of such behaviour. Additionally, it was noted that all non-ADHD participants occasionally showed ADHD symptoms in their music classes. Consequently, the research findings suggest that, in spite of ADHD's generally impairing symptoms, it is possible for an individual with ADHD to engage successfully in music and acquire musical skills. Moreover, when the pedagogy is effective, ADHD need not be a hindrance, but can be integrated into active music making.