Purpose of the Study: This study was undertaken to examine the factors that influence the relationship between Emergency Department (ED) and Mental Health Triage Nurses while caring for clients with a mental illness at the point of triage in the ED. Methods: The site of this study is a busy regional ED and the mental health service that provides a 24 hour triage service to the ED. An Ethnographic methodological approach was used to observe the interactions between the two groups of nurses. Group and individual interviews were undertaken with both cohorts of nurses, extensive field notes were made and the observed interactions and perceptions of the researcher all contributed to the richness of data. This paper will present the findings of this research. Findings: Mental health triage nurses perceived their role as a provider of initial triage assessment services to the ED. In contrast ED nurses relied on the mental health triage nurses to support their practice in caring for clients with a mental illness in the ED. Ongoing mental health nursing presence in the ED was a desirable outcome for ED nurses yet mental health nurses did not perceive this as necessary. Communication between ED triage nurses and MH nurses by phone was identified as the most common yet the most problematic method of communication. These issues created tensions that impacted on collegiality and team work. Recommendations: Where possible mental health clinicians should be based in the ED to be responsible for the assessment and care of clients with acute mental illness and to better equip general trained nurses to provide emergency mental health triage assessment and care.