How to Write a Topic Sentence for a Research Paper


A topic sentence states the main idea of a paragraph. All the other sentences should support this idea by providing details, facts, or pieces of evidence. Just as your thesis statement briefly summarizes the point of your whole paper, a topic sentence should do the same for each single paragraph. In academic writing, a topic sentence usually goes first.

Writing a good topic sentence is not really difficult if you have a clear idea of what the paragraph will be about. However, there are still some rules to follow.

First of all, a topic sentence should include two things: a topic and a controlling idea. The topic is just what it sounds like, and the controlling idea gives your reader a hint of what will follow. For example, “The causes of such a severe financial crisis are attributed to a set of factors.” In this sentence, “a severe financial crisis” is the topic, and “a set of factors” is the controlling idea.

More tips on how to compose a topic sentence:

  • Be clear and concise. Your reader should not be in doubt about what you had intended to say. A short topic sentence facilitates the good flow of a paragraph.
  • Avoid simply announcing your topic. “This part is about the causes of the financial crisis being so severe” is an awkward topic sentence construction. Find a less direct way to provide the same information.
  • Link back to your thesis statement and research topic. Each topic sentence should highlight an important aspect of your subject. Ideally, all your topic sentences grouped together should read as a connected narrative.
  • Do not list any facts or pieces of evidence. You will have enough room for it later in the paragraph. Your topic sentence is to introduce the general idea, not to lay out everything you have to say.
  • Keep your promises. If your topic sentence sounds as “There is evidence to suggest that lowering the drinking age to 18 may help reduce alcohol abuse among teens,” the next sentences in the paragraph should provide the evidence.
  • Avoid quoting. Your topic sentence should demonstrate your own idea, not that of another person. If this particular quote is what you yourself would say about the issue, find a way to paraphrase it and add a bit of your own judgment.
  • Avoid rhetorical questions. This is never a good way to open a paragraph in a research paper.