Since Peplau outlined her perceptions of psychiatric/mental health nursing in (1952) interpersonal relationships has been considered by many as the core of practice. In the intervening period of almost a half century many researchers and theorists have endeavoured to develop and integrate Peplau's framework into day-to-day nursing activity. However, more recently, as a result of the fusion between the professional nursing agenda and the wider political agenda, the importance of interpersonal relationships and the individuality of psychiatric/mental health nursing is being questioned. This questioning is represented in the debate about the aetiology of mental illness, the choice of research methods to determine treatment outcomes and by association the role and value of the psychiatric/mental health nurse. This paper will focus on the interpersonal nature of psychiatric/mental health nursing and explore possible research approaches aimed at explicating its core. Attention will be given to the necessity of using pluralistic methodology in order to do so.