本論文首先從三個面向討論中文對話中的主題不連續現象。第一、當說話者改變主題的時候，停頓較長、話語的自我修正較多，且很少被打斷。第二、說話者可以直接進入新的主題，或者在談論新主題之前提供一些背景訊息。最常使用來引介新主題的是問句，因為說話者可以藉由提出問題邀請其他人一起討論新話題。第三、說話者在開啟話題時通常會利用各種情境資源，包括周遭的環境、說話者共有的背景知識以及在前文談論過的人、事、時、地、物。目前的語料顯示大多數的新主題都與前文有某種程度的關聯。 研究結果亦指出不同層次的對話主題之差異。當說話者引介最高階的對話主題時，他們傾向使用共有的背景知識，並在主題改變的地方提供背景訊息; 他們的話語有較長的停頓和較多自我修正的情境;。相較之下，在開啟其他階層的對話主題時，說話者較常利用前文出現過的訊息，且不傾向在話題一開始的時候提供背景訊息; 他們的話語也較流暢。然而，不同層次的對話主題也有一些共通點。例如，在各個階層中，說話者普遍使用問句引介新話題，而當他們利用前文的訊息改變話題時，新的主題通常和前一個主題有相同的指示對象。 / The present study aims at investigating topic discontinuity in Chinese daily conversations. This pragmatic phenomenon is discussed from three perspectives. First, since changing topics requires more cognitive effort, the speaker who initiates the change is likely to produce longer pauses and repairing utterances, and is fairly unlikely to be overlapped. Second, the speaker can move to a new topic directly, or orient a new topic in various ways. Questions are the most common backgrounded clauses at the topic-shift boundary because they function to invite other speakers to join the new subject. Third, the speaker most frequently draws on some contextual resource to guide other speakers into conversing about the new topic. The most common way is by recycling the prior text. Speech disfluency, grounding, and contextual resources are also found to distinguish various levels of conversational topics. The highest level of conversational topics are usually grounded in general background knowledge, produced with more disfluency, and tend to begin with background information. The other levels of conversational topics, however, are more likely to arise from prior text, more fluently brought up, and do not use background information more often than foreground information at the topic-initial position. Despite the above-mentioned differences, the various levels of conversational topics are similar in several aspects. For example, backgrounded clauses at the topic-shift boundary are mainly questions; topics grounded in prior text predominantly maintain referential continuity across the topical boundary