This article examines the potentiality, acceptability and ethical considerations of a mindfulness-based intervention (MBI) for supporting pupils' mental well-being in a junior school. To date, research has predominantly focused on the psychological or behavioural benefits of MBIs rather than broader and more philosophical issues of implementation. The findings reported in this article are positioned alongside recent debates critiquing the neoliberal agenda of 'privatising' well-being and downplaying the role of the institution and its cultural context. The study synthesises the perspectives of pupils and teachers to provide more in-depth insights into the everyday realities of MBIs in educational contexts. The study highlights and critically examines the inherent ethical dilemmas of implementing MBIs in contexts that include vulnerable and conscripted audiences in particular. As such, this article argues the case for those individuals involved in developing, administering and/or advocating MBIs to acknowledge these ethical dilemmas with greater transparency and integrity and consider the aims of MBIs in relation to their potential instrumental or holistic possibilities and processes of 'schoolification'.