Student democratic participation in schools is often limited to involvement in school councils with associated dangers of tokenism and speaking for others. There is limited space for students to have a voice in what is learned due to mandated state curricula and scepticism about student capacity, even though consultation with students about matters that affect them is a legally binding obligation under Article 12 of the UN Convention on the Rights of the Child. These challenges have resulted in limited research on operationalising substantive student voice. Student agency remains feasible within the boundaries of the formal curriculum, but with significant limitations on decision-making. This paper conceptualises the relationship between student voice and agency, mediated by forms of curricular engagement. We posit that ideological dimensions of engagement and associated student positionality exert a dominant influence on voice and agency. Furthermore, we examine the potential for more authentic approaches to voice and agency to dynamically alter student engagement. Empirically, we draw on work on curriculum negotiation and integration to consider the operationalisation of student voice as the fundamental driver of curriculum, with authentic engagement and agency as emergent properties. Practical considerations for incorporating such approaches in state curricula are explored.