School music has a comparatively low take-up rate as a qualification among English secondary school pupils. Existing research on the issue has proffered possible reasons for this phenomenon but has generally been piecemeal and undertheorised. This paper sets out a fresh theoretical perspective capable of providing a basis for systematic empirical research, and discusses the results of two exploratory studies. Drawing on legitimation code theory, a new approach in the sociology of education that focuses on the basis of achievement within educational contexts, the paper analyses National Curriculum, GCSE syllabi and pupils' attitudes towards a range of school subjects, including music. The documentary analysis highlights that earlier stages of the music curriculum emphasise either musical knowledge or musical dispositions of knowers, but music at GCSE level represents an "elite code" where achievement depends upon both possessing specialist knowledge and being the right kind of knower. The study of pupils' attitudes suggests this code shift is recognised by pupils and may play a role in the low uptake of music for GCSE study. This new framework offers a firmer foundation for future empirical research into attitudes towards school subjects and subject choices.