This article reports on some of the findings from case studies conducted with six secondary school music teachers in New Zealand. The purpose of the study was to investigate and explain the ways in which teachers manage the relationship between classical and popular music in their elective classroom programs, utilizing a theoretical framework drawn from the work of educational sociologist Basil Bernstein and more recent social realist theory. In each case, the focus of the research was the teacher and the influences on their curriculum decision-making. Students in each music department were interviewed to triangulate teacher interviews and observations. The findings indicate that a significant tension is present between the affirmation and validation of students' musical interests and pre-existing skills, and the development of the knowledge considered fundamental within the discipline. It is teachers' ability to "find a balance" between these central concerns of their educational work that is significant in maintaining the epistemic integrity of a subject which has become strongly influenced by socio-cultural influences.