The aim of this study was to investigate the practice profile of emergency nurse practitioners across Australia. Nurse practitioners have been providing health service in the emergency setting internationally for more than 30 years, and evidence supports the value of this role in terms of patient satisfaction, effectiveness in improving service indicators, and acceptability of the role. The introduction of this service model has been instrumental in reducing waiting times for low-acuity patients and impacting positively on emergency department service delivery. Recent rapid uptake of this role internationally has outpaced development of the service model to inform education and ongoing service development. This was a national study that used interpretive research methods to identify the practice profile of emergency nurse practitioners. Data were collected from December 2012 to February 2013 through in-depth interviews. An inductive approach was used in data analysis to identify conceptual themes and develop an analysis framework. The study participants worked in a range of service models and managed patient presentations across all levels of acuity and complexity. The findings show that although there is no single definable model of the emergency nurse practitioner role in Australia, there are practice features that are common across all service models; these have been conceptualized as “modes of practice.” This study has produced new knowledge about the practice profile of emergency nurse practitioners. The findings will inform development of practice standards for education and continuing professional development for emergency nurse practitioners and facilitate standardized operational definitions for ongoing research into this growing service model.