過去二十年間，「教師認同」引起廣泛討論，但關乎「專業英文(ESP)」 老師之相關研究則非常少。本研究檢視一位EAP 課程老師在準備、 教授企業ESP 課程之過程，透過其個人經歷、省思，探討其「教師 認同」發展與角色轉變。資料收集工具包含教師個人課前省思、備 課與授課日誌、雙週訪談、研究後訪談。歸類分析之研究結果顯示， ESP 教師必須吸收大量新知、學習跟學生共同架構知識，扮演ESP 學習議題的問題解決者、在課堂中有著多工角色，在教學方式、課 程進度與活動方面，需持續調整自己。此外，ESP 教師必須調整自 身的不同角色，並解決不同角色之間的衝突。

In the past two decades, different aspects of teacher identity have been widely studied and discussed. However, in the field of English language teaching, the issue of identity among English for Specific Purposes (ESP) teachers seems to be an under-researched topic. This study focused on the narratives of a teacher to gain insight into her identity development during the process of becoming an ESP instructor. Data collection tools included initial reflection (before ESP instruction), learning journal, teaching journal, face-to-face meeting, and follow-up interview. Using the categorical analysis method, the study broke the collected texts into smaller units for descriptive treatment and examined some linguistic characteristics of this participant. The findings indicated an ESP teacher has to be prepared for extensive learning, be engaged in interdisciplinary collaboration, meet the expectations of trouble-shooting for a variety of problems, and undertake multiple tasks during lesson delivery. Most importantly, from EAP to ESP teaching, a teacher faces constant adjustments in teaching approach, lesson pace, and class activity. Therefore, new ESP teachers should be prepared for potential challenges in reconciling identity conflicts for professional growth.