This paper analyses tuitional practices after a major curriculum change (2005) in primary schools of Turkey. Group discussions conducted with teachers and parents in five maximally contrasting schools (e.g. schools in a squatter and a middle-class neighbourhood of Istanbul) show that tuitional practices, being only "loosely coupled" with the official curriculum, are strongly influenced by generation-specific orientations in teachers' organisational milieus, by orientations prevalent in the social milieus of pupils and their parents, and by different forms of capital on the part of teachers, parents and school organisations. Combined with empirical analysis, the paper proposes a theoretical framework that complements the assumptions of New Institutionalism by using the basic concepts of the sociology of knowledge and Bourdieu's concept of capital. This framework offers a new way to understand the intrinsic logic of the growing differences and inequalities within and between school organisations in complex societies.