本研究主要探討在英文敘述文和論說文文本中，英文限定關係子句的篇章功能(discourse functions)。我們主要是從句法、語意、語用和篇章結構(discourse structure)的觀點，來探討限定性關係子句的功能與它在篇章單位(discourse unit)所出現的位置有何關聯。研究結果顯示多數的限定性關係子句出現在篇章單位最前面的位置，而且他們往往引導他們新的先行詞(new head NPs)作為整個篇章單位的主題(topic)。因此我們認為，大多數限定性關係子句會出現在篇章單位最前面的位置，是因為它們有一個很重要的篇章功能，那就是它們要引介新的先行詞作為整個篇章單位的主題。此外，本論文也探討大學英文系學生在他們的英文寫作中，使用限定性關係子句的情形。研究結果發現，在大學生的寫作中，限定性關係子句的先行詞常是泛指，而且限定性關係子句的內容常常是舊有的訊息。因此，台灣大學生鮮少使用限定性關係子句來引導新的先行詞作為篇章單位的主題。我們推論大部份學生並未習得限定性關係子句的篇章功能。本論文根據此研究結果提出一些在英語教學上的建議：在課堂上教導英文限定性關係子句時，應以篇章單位為主，使學生了解限定性關係子句的篇章功能。 / The findings of the previous studies on discourse functions of English restrictive relative clauses are mainly based on spontaneous conversations and written narrations. Rare studies were found on the discourse functions of English restrictive relative clauses in written data. The purpose of the present study, thus, is to investigate the discourse functions of English restrictive relative clauses in written expositions and argumentations by native speakers of English. Also, we study the use of English restrictive relative clauses in the compositions by Taiwanese college students. In particular, we want to know how the discourse functions of English restrictive relative clauses are related to their occurrences in discourse structures. Thus, our analysis includes considerations from four dimensions: syntax, semantics, pragmatics and discourse. We found that the majority of English restrictive relative clauses occur in the beginning position of discourse units. And they serve as a device to introduce their new head NPs as the topics in the subsequent discourse when occurring in such a position. Therefore, we conclude that the main purpose of using a restrictive relative clause is to introduce a new head NP as the topic when the new referent is firstly mentioned in a new discourse unit. Moreover, we examined English restrictive relative clauses in the compositions by English Department juniors to see if the factors found in native speakers’ writings are also at work in their compositions. We found that students have not fully understood the discourse functions of English restrictive relative clauses. Based on our findings, we offer pedagogical implications with the aim of hoping that students can learn the discourse functions of English restrictive relative clauses.