Abstract: This article draws on empirical evidence to illustrate the core role of nurse practitioners in Australia and New Zealand. A study jointly commissioned by both countries' Regulatory Boards developed information of the newly created nurse practitioner role, to develop shared competency and educational standards. This interpretive study used multiple data sources, including published and grey literature, policy documents, nurse practitioner programme curricula and interviews with 15 nurse practitioners from the two countries. The core role of the nurse practitioner was identified as having three components: dynamic practice, professional efficacy and clinical leadership. Nurse practitioner practice is dynamic and involves the application of high level clinical knowledge and skills in a wide range of contexts. The nurse practitioner demonstrates professional efficacy, enhanced by an extended range of autonomy that includes legislated privileges. The nurse practitioner is a clinical leader with a readiness and an obligation to advocate for their client base and their profession at the systems level of health care.