This research project explores the meanings twin participants make of their twinship. The focus is the subjective experience of being a twin, with a view to considering what might be needed from a therapist working with a twin patient. Hermeneutic phenomenology provides a foundation for the research, which comprised a thematic analysis of interview transcripts. The themes identified were conceptualised as ?oneness?, ?twoness?, and ?threeness?; these describe respectively the experiences of twins as a single unit, as an individual within the pair, and in relation to a third person such as the therapist. It is suggested that the therapist working with a twin patient will need to acknowledge the twin?s oneness and twoness, whilst accepting their own position as third in a non-intrusive manner.