This article draws upon findings from fieldwork conducted with Chilean mental health practitioners and school staff to explore how children's mental health diagnoses can be used in the school setting as a particular rationale to mobilise and convey new forms of care practices (Mol, The logic of care: Health and the problem of patient choice, 2008). Inspired by the framing of care as an interrelational, interdependent and more-than-human affair promoted by Science and Technology Studies, and drawing from conceptual tools offered by post-humanist approaches, we focus our examination on the diagnosis of attention deficit-hyperactivity disorder (ADHD). Following the diagnosis since its formulation by clinicians in the public sector to its enactment in an urban school in Santiago, Chile, we explore how certain caring/uncaring practices are enacted in relation to the diagnosis, reconfiguring the classroom by incorporating (non)human actors to care for the diagnosed child. However, care is ambivalent, and the diagnosis can be put into action for other purposes as it interweaves with educational policies and other agendas. Thus, to produce policies that truly foster inclusion, attention must be given to the micropolitical level where disabilities and disorders are enacted, developing appropriate ethico-political and affective sensitivities to care accordingly.