This article presents the findings of a review of the first year of a night emergency department (ED) mental health triage and consultancy service. During the first 12 months of operation of the service, data on key performance indicators were entered into an emergency mental health triage and consultancy database. Data were also obtained from pre- and post-satisfaction surveys completed by ED staff and from self-appraisal statements generated by the five mental health nurses who undertook the position during the review period. The findings show the ED mental health triage and consultancy service positively impacted on the functioning of the emergency department. This was evidenced by staff’ perceptions regarding the value of the service and through shorter “seen by times”, a reduction in the number of patients with psychiatric/psychosocial problems who left the department without being seen, and the effective management of patients presenting with psychiatric/psychosocial problems, particularly those presenting with deliberate self-harm. The review provided evidence regarding the value of the emergency mental health triage and consultancy service and highlighted the advanced practice role undertaken by mental health nurses in this position.