本研究旨在讨论中文作为第二语言课程发展与实施过程中的课堂语言政策问题，特别是课程设计者、教师及学生在实际教学环境中如何看待并使用学生母语进行第二语言教学的问题。本文回顾了香港中文二语教育对保障少数族裔教育权利的重要性，梳理了教学媒介语与教学法的相互依存关系，并分析了两种主流课堂语言政策的理论源头与实践情况。在此基础上，本文以一门初级中文二语课程为研究案例，利用问卷、小组焦点访谈，个人访谈及课堂观察的混合型研究方法调查了课程主要持份者对课堂语言使用的态度。研究发现，课程设计者、教师及学生对于课堂媒介语政策的态度存有明显分歧，对中文二语教学中使用英文作为通用语言的态度差异较大。本文认为目前香港中文二语教学实践所推崇的沉浸式教学模式不符合实际教学需求，一刀切的单语教学政策更不是迅速提升少数族裔中文水平的灵丹妙药。香港在制定少数族裔中文第二语言学习政策时，应尊重中文作为第二语言教学的规律，重视学生母语在目的语教学中的重要作用，加强相关实证研究和教师培训。

This study explores the complexity of classroom language policy in the process of developing and implementing a Chinese as a Second Language (CSL) course in Hong Kong with a focus on the diverse attitudes of course developers, teachers and students. It begins with a brief introduction of the current CSL education policies for ethnic minorities in Hong Kong, followed by a critical review of the covert and overt classroom language polices, and the theoretical foundations for ideologies and practices behind the monolingual and multilingual pedagogies in CSL teaching and learning. Taking an adult beginners' CSL course as an example, this study has collected both qualitative and quantitative data through questionnaire, focused-group interview and one-on-one interview with course developers, teachers and students. The study found that the key stakeholders of the course had different perspectives towards classroom language policy, and different levels of needs of English as a supporting medium. Findings of the study suggested that the monolingual pedagogy failed to reflect the classroom reality. A one-size-fits-all immersion pedagogy is not the 'cure-all' for ethnic minority students to become native speakers of Chinese overnight. Policymakers in Hong Kong should respect the basic principles for teaching and learning of Chinese a second language, and allocate more support for teacher education. More research work is required to improve our understanding of the complex relationships between and functions of L1 in L2 teaching.