Lau, Tsz LuiTsz LuiLauDr. PANG Lan-szeDr. TONG Ka-Ho, AdrianAdrianDr. TONG Ka-HoSze, Yim Binh FelixYim Binh FelixSze2026-08-032026-08-032026Lau, T. L., Pang, L.-S., Tong, K. H., & Sze, Y. B. F. (2026, June 24–27). The therapeutic triangle: A multiperspective interpretive phenomenological analysis of sign interpreter-involved psychotherapy. Society for Psychotherapy Research (SPR) 57th International Annual Meeting, Osaka, Japan.http://hdl.handle.net/20.500.11861/28394In the Deaf community worldwide, sign interpreters (SI) serve as a crucial bridge to mental health access. Sign interpreter-involved psychotherapy creates a triadic therapeutic structure that fundamentally challenges traditional dyadic therapeutic relationship dynamics. The qualitative study using Multiperspective Interpretive Phenomenological Analysis took a first step toward understanding the lived experience of all parties in an SI-involved psychotherapy space in Hong Kong. Four clinical psychologists, four sign interpreters, and three Deaf/Hard of Hearing (D/HH) clients participated in 2-hour semi-structured individual interviews. This study identified two primary themes: Ethics and Trust Dynamics. Within the theme of Ethics, two specific subthemes emerged: (1) transference and countertransference, occurring both between the therapist and the SIs, and between the SIs and D/HH clients; and (2) boundary crossings due to SIs’ overbearing role. Under the theme of Trust Dynamics, two additional subthemes were identified: (1) the impact of pre-existing relationships between SIs and clients; and (2) the therapist’s multicultural sensitivity and their therapeutic positioning. SI-involved psychotherapy presents a unique therapeutic dynamic and therapeutic challenges that are absent in dyadic psychotherapy. The findings provide insights into culturally responsive practices serving marginalized linguistic communities, suggesting that role induction amongst three parties before psychotherapy and culturally sensitive ethical training for therapists are warranted. Future research direction and clinical implications will be discussed. Keywords: Interpreter-involved psychotherapy, Therapeutic alliance, Multiperspective Interpretive Phenomenological Analysis, Deaf mental health, Multicultural counsellingenConference Paper