With the relentless increase in the number of converter academies, the already fragmented secondary school system is fracturing still further. Since branching points, partitions and choice are all known to contribute to inequalities, the urgency to fully understand the roots and effects of marginalisation has never been greater. What can be done to pre-empt vulnerable/socially disadvantaged students from becoming marginalised and disengaged? What are the implications for best practise within schools and the ramifications for system structures? This ethnographic study addresses the experience of marginalisation of a small group of secondary school students. It seeks to give a voice to these students as a way of understanding the triggers, causes, effects and consequences of disengagement from mainstream education. The student participants in the research have all spent some time removed from the mainstream classroom setting in a withdrawal-unit, most commonly following a period of sustained low-level disruption. The research is primarily based on semi-structured interviews, with some additional participant observation, as well as small group or one-to-one teaching undertaken by the researcher within this unit. The data gathered is analysed through a process of grounded theory and the categories emerging from this indicate that there is a range of factors which students perceive as fuelling their marginalisation within the secondary education system. Some of these factors are associated with system structures, issues of transition, groupings and pathways. Others stem from their experience in the classroom or relate to labelling and issues of identity. While several piecemeal interventions are noted, to really take the students' experience seriously, I argue, entails moving beyond reforms and adaptations, to think about education differently. What is needed to tackle and eradicate this marginalisation, is a radically comprehensive education system structure, with 'the social' at its heart, where critical pedagogy is realised.