Aim: To describe how nurse coordinators accomplished day-to-day interprofessional coordination in an Australian emergency department team, drawing some lessons for the design of nurse coordinator roles in other settings. Background: Previous studies have examined leadership within nursing teams, and there are a growing number of registered nurses employed as care coordinators. There is limited literature on how the day-to-day coordination of interprofessional teams is accomplished, and by whom. Method: Nineteen semi-structured interviews with emergency department registered nurses, doctors and nurse practitioners analysed thematically. Results: Three themes describe how coordinators accomplished interprofessional coordination: task coordination and oversight, taking action to maintain patient flow and negotiating an ambiguous role. Conclusion: Better-defined nurse coordinator roles with clearer authority and associated training are essential for consistent practice. However, accomplishing interprofessional coordination will always require the situated knowledge of the complex nursing-medical division of labour in the workplace and the interpersonal relationships that are only gained through experience. Implications for Nursing Management: The design of nurse coordinator roles must include the thorny question of ‘who leads’ interprofessional teams in the day-to-day coordination of tasks. New and inexperienced nurses may not have the necessary situated knowledge or interpersonal relationships to succeed. However, such roles offer an important development opportunity for future nurse managers.