Although there is much written on the emotional labour of nursing, there is little research grounded in the experience of so-called ‘unqualified’ care assistants. This paper is drawn from an ethnographic study conducted with care assistants on three dementia care wards in one mental health trust within the United Kingdom National Health Service (NHS). We describe the emotional labour carried out by care assistants in their attempts to provide personalised care for people whose cognitive degeneration renders conventional relationship-building very difficult, produces unpredictable ‘challenging behaviour’ and calls into question the notion of ‘feeling rules’. This context requires the ability to strike a balance between emotional engagement and detachment, and it is the complexities of this relationship that are the focus of this paper, arguing that a degree of detachment is a prerequisite to engagement in this context. In conclusion, we argue that the contribution of care assistants in this context needs to be better acknowledged, supported and remunerated.