The current paper reports on the impact of an increase in school-based music training on a range of cognitive and psychosocial measures for 10-13-year-olds in two independent studies. In the first study, the benefits of increased frequency of classroom-based music classes were compared with classroom-based drama and art lessons in secondary school students (N = 127). The second study compared the effects of introducing a new classroom-based music programme with a new drama programme for primary school students (N = 100). Assessments were obtained at baseline and approximately six months after implementation of each programme. In contrast to previous research on the effects of private music tuition, no convincing benefits of school music classes were apparent. Trends of interest were observed in non-verbal intelligence, aggression scores and verbal memory, which require further investigation. The findings suggest that the benefits of music instruction previously reported may be limited to private or externally-based music tuition, or socioeconomically disadvantaged schools. The intrinsic value of music education for enjoyment and learning should therefore remain central to the justification of music education in the national school curriculum.