本研究旨在於觀察對話者之間的熟悉度對於外語學習者的語言影響。溝通互動性質的作業能提供語言學習者機會來對話；然而，很少有學者研究對話者之間的社會層面對於溝通互動的影響。在此研究中，實驗對象是一群台灣的高一生，程度介於全民英檢初級和中級之間，他們依彼此間熟悉程度的調查而分成19個熟悉組和不熟悉組，並進行三種不同性質的溝通作業，再分別計算negotiation for meaning，language-related episodes，和recasts的使用次數。量化分析的結果顯示對話者之間的熟悉度並沒有造成以上三種溝通特性的顯著性差異，唯有在作業類型中有顯著性差異。但質性研究發現由於權力關係帶來的張力，對話者間的熟悉度會因著面子的考量而造成互動模式的些微差異，對於學習者的情意層面、投入程度和溝通策略的使用產生一定的影響。此結果將對於語言課室中配對練習有重要的教學啟示。 / The purpose of this paper is to observe how the interlocutors' familiarity influences the language produced by EFL (English as a foreign language) students. It is widely argued that communicative language tasks may provide learners with opportunities to manipulate and modify their language productions, which in turn helps learners develop their target language. However, few studies concern the social dimension of interlocutors in task-based interactions. In this study, some senior high school English learners in Taiwan were divided into 19 familiar and 19 unfamiliar pairs. Every dyad was engaged in the picture differences task, the describe-and-draw task, and the discussion task. Negotiation for meaning, language-related episodes, and recasts viewed as crucial to second language acquisition (SLA) were interactional features used for quantitative analysis. The results showed that interlocutor’s familiarity had no significant effect; only in task types did the researcher find discernable differences. Opposed to such negative results, the qualitative analyses showed a divergence of interactional patterns due to the face issue resulting from social dynamics. Learners’ interloctutors’ familiarity, which may impact learners’ affective domain and conversational strategy use, may bring some pedagogical implications for pair work in second language classroom teaching.