The study of student participation in decision making has been characterised by conceptual vagueness and an absence of empirical tools to compare participatory practices in various contexts and to determine when they achieve their goals. This study presents an integrative theoretical model grounded in the organisational literature on participative decision making (PDM) -- particularly on teacher participative decision making -- as well as in the children's participation literature. The model focuses on decisions having collective implications made by a group of students or a group of students and adults. It views student participative decision making as a multidimensional structure that emerges within a context. Specifically, the model suggests that the rationales behind promoting student participative decision making (pragmatic, moral, or developmental/pedagogical) will determine its dimensions, which, in turn, will affect student, teacher and school outcomes. It posits that the school organisational culture will shape the patterns of these relationships. The model answers repeated calls in the children's participation literature for frameworks that are more attentive to diverse cultural environments. It provides an empirical foundation for comparative studies to explore how student participative decision making is interpreted, perceived and implemented in different organisational cultures.