句子的主題具備了串連訊息、引導文句發展的重要功能，然而資料顯示許多外語學習者常因為使用不適當的主題而影響語句的連貫性以及文章的流暢度。本研究透過觀察台灣高中生記敘文的主題類型，分析其在高、中、低分群學生文章中的使用情形來了解主題的選用對文章連貫性以及整體作文品質的影響。 本研究分成初步試驗以及正式研究兩階段，在初步試驗階段我們建立了分析的架構。在正式研究階段，我們採集111位高三學生於課堂上完成的記敘文並交由兩位經過訓練的閱卷老師進行評分，最後結果產生高、中、低分三組學生作文，接著再從每一組的文章中各抽樣10份進行主題類型之分析研究。 分析結果顯示，三組學生作文的主題類型及出現頻率大致雷同，整體而言，學生最喜好使用非標記的名詞主題，卻最少使用標記的分詞+名詞主題。然而進一步分析三組的主題發展情形，卻發現有顯著的組別差異，以高分群為例，其主題多具備銜接上文或有利推進文意的背景資料文字，相較之下，中等或低分群的作文比較容易出現和上下文不相關或中斷文意發展的新主題。 根據本研究的發現，我們建議在英語作文課中介紹句子主題的概念，幫助學生熟悉其類型和功能，期使學生能在記敘文文章中正確使用主題來達到語句連貫，文意流暢的溝通目標。 / Theme plays a significant role in guiding the information flow in text. Nonetheless, there is evidence indicating that many EFL learners often fail to make good choices of theme to secure sentential relationship or writing coherence. Through the observation on the occurrences and distribution of theme types in three levels of student compositions: the high, the middle and the low-rated narratives, the present study aims to investigate the establishment of theme in Taiwanese senior high school students’ narratives in order to gain understanding of theme’s effect on writing coherence and writing quality. The entire study consists of a pilot study and a formal one. The pilot study helps establish the criteria for the main study. In the main study, 111 student compositions were gathered and two raters were recruited and trained for the rating. Based on the rating system, the student compositions are divided into 3 levels. 10 samples from each level were randomly selected for thematic analysis. The result shows that the occurrences and distribution of theme types in the three levels of writing are alike. In general, unmarked NP theme is the most favored by all the students and marked theme Non-fi C + NP is the least desirable. Nonetheless, in terms of the establishment of theme, there are major differences between groups. In particular, the high-rated essays tend to establish a theme that is connected to the theme or the rheme in the preceding discourse or provides background information for the development of the event. In contrast, the mid-or low-rated essays are more likely to establish a theme that is unrelated or disruptive to the progression of the current discourse. Based on the findings of the present study, it is suggested that the notion of theme including its features and functions be incorporated into the teaching of English compositions to help Taiwanese senior high school students identify the characteristics of coherent writing and facilitate coherence in their English narratives.