Objective: To evaluate the impact of an organisational intervention aimed to reduce occupational stress and turnover rates of 55% in hospital nurses. Design: The evaluation used a pre- and post-intervention design, triangulating data from surveys and archival information. Setting: Two public hospitals (H1 and H2) in the Northern Territory (NT) Australia participated in the intervention. Subjects: 484 nurses from the two NT hospitals (H1, Wave 1, N=. 103, Wave 2, N=. 173; H2, Wave 1, N=. 75, Wave 2, N=. 133) responded to questionnaires administered in 2008 and in 2010. Measures: The intervention included strategies such as the development and implementation of a nursing workload tool to assess nurse workloads, roster audits, increased numbers of nursing personnel to address shortfall, increased access to clinical supervision and support for graduates, increased access to professional development including postgraduate and short courses, and a recruitment campaign for new graduates and continuing employees. We used an extended Job Demand-Resources framework to evaluate the intervention and 17 evaluation indicators canvassing psychological distress, emotional exhaustion, work engagement, job satisfaction, job demands, job resources, and system factors such as psychosocial safety climate. Turnover rates were obtained from archival data. Results: Results demonstrated a significant reduction in psychological distress and emotional exhaustion and a significant improvement in job satisfaction, across both hospitals, and a reduction in turnover in H2 from 2008 and 2010. Evidence suggests that the intervention led to significant improvements in system capacity (adaptability, communication) in combination with a reduction in job demands in both hospitals, and an increase in resources (supervisor and coworker support, and job control) particularly in H1. Conclusions: The research addresses a gap in the theoretical and intervention literature regarding system/organisation level approaches to occupational stress. The approach was very successful on a range of health, work outcome, and job design indicators with results providing compelling evidence for the success of the system/organisational level intervention. The quasi-experimental design enabled us to conclude that improvements for the nurses and midwives could be attributed to the organisational intervention by the NT Department of Health (DoH). Further research should be undertaken to explore longer-term impacts, and particularly the influence on turnover. Levels of stress in hospital nurses remain high and present important implications for the psychological well-being of staff.