一個段落 (paragraph) 是一組討論一個單一主題與主旨的句子，它包含一個主旨與支持發展該主旨的句子。當寫作較長的文章時，段落可以幫助寫作者整理想法，它是一個想法的單位。
一個段落的組織結構通常包含三部分：
1. 主題句 (topic sentence)：指出一個段落的主旨 (main idea) 與目的 (purpose)，通常包含主題 (topic) 與主題論述 (controlling idea)
範例：〔A person can be a good communicator〕｛by being a good listener｝. (主題用 〔 〕標示、主題論述用 ｛ ｝標示)
2. 支持句 (supporting sentence)：支持與發展該段落主題句中的主旨，支持句的類型包含解釋 (explain)、描述 (describe)、提供原因 (give reasons)、提供事實 (give facts)、舉例 (give examples)、提供引語 (give quotations) 等。
範例：When speaking with someone, a good listener pays close attention to the speaker’s words while looking at his or her face. A good listener also shows interest by smiling and nodding. Also, posture is important; it can affect communication for both the speaker and the listener. For instance, sitting slumped in a chair makes a person seem passive, while a relaxed posture with the body bent slightly forward shows interest in the speaker and the conversation. Remember, too, that good communicators do not interrupt while someone is speaking; although interruption is active participation, it can be impolite. (使用了解釋、提供原因、提供範例等支持句)
3. 結論句 (concluding sentence)：標示段落的結束，並提醒讀者此一段落的重點。寫作結論句常重申其主題句，對主題句做更具體詳細的說明、連結回全文主旨、或表達作者對於主題句的看法 (一個段落未必須包含結論句)。
範例：Juan took the first step toward improving his class performance by simply sitting in the front of the classroom each day. (重申主題句，並連結回全文主旨，指出坐在教室前面可以增進課堂表現。)
最後我們再來看一個比較學術的段落，小編分別標示出其主題句、支持句、結論句，以更清楚觀察其組織結構與寫作邏輯，來複習以更熟悉段落的寫作概念：
主題句：The means by which environmentalists seek to achieve their political goals demonstrate a willingness to operate within traditional political channels. [point arguable: some people may believe environmentalists largely use antidemocratic strategies.]
支持句：Like many other special interest groups, advocates for the environmentalist movement use lobbying tactics such as contributing financially to the campaigns of environmentally friendly candidates. Lobbying provides a source of political influence and power. As one analyst of environmental politics notes, in “making some commitment to work within the political system. . .[environmental lobby groups] succumb to. . .pressure to play ‘by the rules of the game’ in the compromise world of Washington, D.C.” (Vig and Kraft 70). [blend of supporting evidence/analysis]
結論句：Some might argue that environmentalists have taken a distinctly antiAmerican approach to policy change, claiming that lobbying is inherently undemocratic in its bias towards certain segments of the population; however, lobbying remains a constitutionally legitimate form of political activism. [more than just a summary, the point is arguable and could easily lead to another point.]
References: Longman Academic Writing Series, Great Writing, Steps to Writing Well
https://www.hamilton.edu/documents/Paragraph%20Structure.pdf
https://www.siue.edu/....../Writing%2520a%2520Paragraph.html
