Objective. Allied health structures and leadership positions vary throughout Australia and New Zealand in their design and implementation. It is not clear which organisational factors support allied health leaders and professionals to enhance clinical outcomes. The aim of this project was to identify key organisational contexts and corresponding mechanisms that influenced effective outcomes for allied health professionals. Methods. Aqualitative realist evaluation was chosen to describe key aspects of allied health organisational structures, identify positive outcomes and describe how context and processes are operationalised to influence outcomes for the allied health workforce and the populations they serve. Results. A purposive sample of nine allied health leaders, five executives and 49 allied health professionals were interviewed individually and in focus groups, representing nine Queensland Health services. Marked differences exist in the title and focus of senior allied health leaders' roles. The use of a qualitative realist evaluation methodology enabled identification of the mechanisms that work to achieve effective and efficient outcomes, within specific contexts. Conclusions. The initial middle range theory of allied health organisational structures in Queensland was supported and extended to better understand which contexts were important and which key mechanisms were activated to achieve effective outcomes. Executive allied health leadership roles enable allied health leaders to use their influence in organisational planning and decision-making to ensure allied health professionals deliver successful patient care services. Professional governance systems embed the management and support of the clinical workforce most efficiently within professional disciplines. With consistent data management systems, allied health professional staff can be integrated within clinical teams that provide high-quality care. Interprofessional learning opportunities can enhance collaborative teamwork and, when allied health professionals are supported to understand and use research, they can deliver positive patient and business outcomes for the health service.