Engaging black and minority‐ethnic (BME) individuals in therapy and maintaining a positive therapeutic alliance can be a complex task, especially when challenging a family's core belief system. This study examines how therapists working within a specialist cultural service in London, UK were able to question a family's core cultural belief system whilst building and maintaining a strong therapeutic alliance. Video‐assisted semi‐structured interviews were carried out with two family members and their two therapists, and analysed using thematic analysis. The findings suggest that core beliefs can be effectively challenged within the context of a strong therapeutic alliance if topics are approached in a sensitive and respectful manner, by trusted therapists who have a degree of knowledge and awareness of their own cultural positioning, as well as an understanding of their clients’ culture. We propose that engaging with culture in this way can strengthen alliance and facilitate positive change. Practitioner points Core cultural belief systems can be effectively challenged by therapists within the context of a positive therapeutic alliance Topics need to be approached sensitively with a degree of authenticity, curiosity and respect Respectfully challenging core beliefs while being aware of one's own cultural construction and positioning, can strengthen the therapeutic alliance and promote positive change 挑战核心文化信念, 维护治疗同盟：定性研究 使黑人和少数族裔个体参与治疗和维持积极的治疗同盟会是一项复杂的任务, 特别是在挑战家庭的核心信念系统时。这项研究调查了英国伦敦的一家专业文化服务机构的治疗师如何能够在质疑一个家庭的核心文化信仰系统的同时, 建立并保持强大的治疗同盟。我们对两名家庭成员及他们的两名治疗师进行了视频辅助的半结构访谈, 并用主题分析法对访谈进行了分析。研究结果表明, 如果以敏感和尊重的方式谈及话题, 且治疗师受到信任、充分了解和意识到自己的文化定位, 并了解来访者的文化, 那么核心信念在强大的治疗同盟的环境下可以有效地受到挑战。我们提出, 这种方式处理文化可以加强同盟, 促进积极的变化。 对实务工作者的启示 在积极的治疗同盟的环境下, 治疗师可以有效地挑战核心文化信仰系统 谈及话题的时候需要一定程度的真实性、好奇心和尊重 在意识到自己的文化构建和定位的同时, 以尊重的方式挑战核心信念, 能够加强治疗同盟, 促进积极改变 关键词：文化；治疗同盟；家庭信念；定性研究；黑人和少数族裔来访者群体