Rising dementia incidence is likely to increase pressures on healthcare services, making effective well coordinated care imperative. Yet, barriers to this care approach exist which, we argue, might be understood by focussing on identity dynamics at the frontlines of care. In this article, we draw upon findings from an ethnographic study of healthcare assistants (HCAs) from three dementia wards across one National Health Service mental health trust. Data revealed that the HCAs are a close-knit 'in-group' who share low group status and norms and, often highlight their own expertise in order to promote self worth. HCAs' social identity is considered as a barrier to effective teamwork with strong ingroup behaviour suggested as a consequence of their marginalisation. We explore these findings with reference to social identity theory (Tajfel, 1974; Turner, 1978 ) and discuss implications for delivering multiprofessional and interprofessional care.