Abstract: This study using action research involving twelve registered nurses worked toward improving nursing care in an acute mental health in-patient service. Following focus groups with consumers, families, nurses, doctors, and allied health professionals, the action research group developed projects over eighteen months to improve continuity and consistency of nursing care. There was a subsequent restructuring of nursing service to better define leadership, accountability and to strengthen care delivery. The second half of the thesis involves a critical social analysis of the research data and produces a theory of mental health nursing which, the author suggests, has wide application in practice.