Changes to the work of registered nurses (RNs) has generated increasing concern about the ways in which HCAs are used and the basis for the division of nursing work tasks and roles. The theoretical and empirical foundations upon which these divisions lie are often weak. Empirical data are often lacking, or of sufficiently poor quality to be questioned. This thesis seeks to understand the division of work between HCAs and RNs in adult general care in one acute NHS hospital. The thesis makes use of an interactionist perspective to frame the study's examination of the micro-social processes surrounding the daily negotiation of HCAs' work. In doing so, connections are made to the wider (macro) processes that influence nursing work. An in-depth case study approach using documents, survey, interviews, focus groups and participant observation was used to collect data on the demographic and biographic characteristics of HCAs; their perceptions of their work; the nature of observed work; the ways in which their work is supervised; their interactions with other nurses; and RNs' perspectives of HCA work. National, professional and organisation policy expectations emphasise the HCA role as one of assisting RNs under their supervision. This study reveals significant deviation from these policy goals. The workplace arena - and the negotiations that take place in it — actively shapes HCAs' work and yet policy makers often appear to disregard this characteristic. Differing amounts of power associated with the occupational groups in hospitals influence the nature and outcome of work-related negotiations at the organisational level - the results of these negotiations are variable, and lead to dynamic patterns of use, non-use and misuse of the HCA resource. These patterns led to some unintended outcomes: a resentful workforce, the creation of gaps in the application of nursing care, and traditional quality assurance mechanisms left wanting.