The need for Registered Nurses (RNs) in the long-term care of older people is being questioned, particularly in the context of nursing shortages, while suggestions for 'professionalising' Care Assistant (CA) roles are emerging. Despite ongoing debates about the importance of their work, research has so far been unable to provide an evidence-base for the outcomes of the work of either RNs or CAs in UK care homes. Using a multi-method interpretive approach, adopting a structure-process-outcome framework and grounded in the philosophical hermeneutics of Hans-Georg Gadamer, this qualitative research sought to illuminate the distinct contributions made by RNs and CAs to outcomes for older people in care homes. RNs and CAs from around the UK contributed 'significant' examples of their work for Phase 1 of the study and Phase 2 comprised researcher fieldwork (observation, interviews and documentary analysis) in three care homes around England. Participants included RNs, CAs, older residents, relatives, home managers and professionals working in the homes. The findings offer a rich and detailed analysis of the realities of the work, much of which takes place 'behind closed doors' and has been described to a limited extent in the literature. They suggest that the CAs' daily support helps residents to function and to feel valued, and that close, reciprocal, family-type relationships develop. The health knowledge and clinical expertise of good RNs is critical in determining residents' health outcomes, particularly in the long-term, and RNs' 24-hour 'perceptual presence' can make life or death differences in acute or emergency situations. RNs also influence the environment, atmosphere and quality of care in the home. In the context of the literature, the findings offer new insights into the role and contribution of RNs and CAs, the outcomes of their work and the priorities of residents. The study produced new models of RN and CA roles in care homes, encompassing dimensions not previously acknowledged in the literature or their job descriptions, and a new framework within which the outcomes of care for older people could be evaluated. The research offers a positive image of work with older people in independent sector care homes.