英語授課（English Medium of Instruction, EMI）的教育模式在非英語為主要語言的國家中已經成為一種重要的教學方法。本文主要探討EMI的定義、目的、理論、類型、模式以及相關的挑戰和趨勢。其中，EMI的主要目的包含：一、提高學生的英語能力並增進學術知識，為未來的就業做好準備；二、推動文化轉變，促進跨文化了解，並創造國際交流與合作的機會。然而，EMI也面臨一些挑戰，例如對教師和學生帶來語言和認識論上的挑戰、對不同語言和文化背景的學生造成不公平。EMI的類型和模式因學術機構和情境而異，透過EMI，英語成為不同母語者之間的溝通工具，強調有效的跨文化交流。EMI要求學生發展學術識字能力，並在學術上有效使用語言和其他資源。EMI的挑戰也包括教師和學生的語言能力和認識論挑戰，以及學習評量結果是否能反映英語能力或學科知識。為了因應這些挑戰，需要提供師資培訓和語言支持並整合語言與內容學習，以確保EMI的品質和提供學生支持。EMI強調語言相關支持措施的提供，例如英語語言課程和學術寫作工作坊，以協助學生提高英語使用能力並獲得學業成功。相關政策也引領了EMI趨勢，例如波隆納進程（Bologna process）和聯合國教科文組織（United Nations Educationnel, Scientific and Cultural Organization, UNESCO）的教育語言政策鼓勵語言多樣性和公平性，為提高英語能力和學術知識，並推動跨文化交流，EMI在非英語為主要語言的國家中被廣泛使用。

English as a Medium of Instruction (EMI) has become an important teaching method in countries where English is not the primary language. This article primarily explores the definition, purposes, theories, types, modes, challenges, and trends associated with EMI. The primary purpose of EMI is to enhance students’ English language proficiency and deepen their academic knowledge to prepare them for future career prospects. Additionally, EMI facilitates cultural transformation, promotes cross-cultural understanding, and creates opportunities for international exchange and collaboration. However, EMI also faces various challenges, including linguistic and epistemological challenges for teachers and students, resulting in inequality among students from diverse linguistic and cultural backgrounds. The types and modes of EMI vary based on academic institutions and contexts. Nevertheless, EMI emphasizes English as a means of communication between individuals with different native languages, highlighting effective cross-cultural communication. EMI requires students to develop academic literacy skills and effectively use language and other resources within an academic context. Challenges of EMI include the language proficiency and epistemological challenges faced by teachers and students, as well as the question of whether assessment outcomes reflect English language proficiency or subject knowledge. Addressing these challenges necessitates providing teacher training and language support, as well as integrating language and content learning to ensure the quality of EMI and support for students.