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: Using a thematic framework to guide analysis, data was broadly categorised into 1) communication and the factors that affect interdisciplinary communication, 2) the individual nurse as the point of difference, 3) the triage scale and its influence on the referral and response process and 4) the different processes that underpin ED and mental health triage roles.