Topic Sentences


What is a Topic Sentence and Why is it Useful?

Imagine reading one long block of text, with each idea blurring into the next. We are likely to lose interest in writing that is disorganized and spans many pages without breaks. Paragraphs separate ideas into logical, manageable chunks. By exploring one idea at a time, the writer has a chance to explain and support that idea. The reader can then digest the idea before moving on to the next related paragraph.

topic sentence is a sentence that summarizes the main idea of a paragraph, just as a thesis summarizes a whole essay. As the unifying sentence for the paragraph, the topic sentence is the most general, whereas other supporting sentences provide more specific information, such as facts, details, or examples.

Each topic sentence should clearly relate to the essay’s thesis. We will talk more about how to make that connection in 21.4 “Flow, Cohesion, and Transitions in Paragraphs.


An illuminated light bulb representing an idea is surrounded by chalk drawings of ovals representing subsidiary ideas.
Image 4.1 (Credit: “Clear Light Bulb” by Pixabay from used according to CC0.)

What makes a Good Topic Sentence?

The goal of a topic sentence is to help readers focus on and remember the main idea of the paragraph. So the trick is to write a sentence that covers all the points of the paragraph but does not cram in too many words or details.  We want to give a sense of what the paragraph will contain without listing all the specifics.

Vague topic sentence: “First, we need a better way to educate students.”

Explanation: The claim is vague because it does not provide enough information about what will follow, and it is too broad to be covered effectively in one paragraph.

Revised version: “Creating a national set of standards for math and English education will improve student learning in many states.”

Explanation: The sentence replaces the vague phrase “a better way” and leads readers to expect supporting facts and examples as to why standardizing education in these subjects might improve student learning in many states.

In addition, we want to make sure that the topic sentence gets right to the point. A good topic sentence is clear and easy to follow.

Confusing topic sentence: “In general, writing an essay, thesis, or other academic or nonacademic document is considerably easier and of much higher quality if you first construct an outline, of which there are many different types.”

Explanation: The convoluted sentence structure and unnecessary vocabulary bury the main idea, making it difficult for the reader to follow the topic sentence.

Revised version: Most forms of writing can be improved by first creating an outline.

Explanation: This topic sentence cuts out unnecessary verbiage and simplifies the previous statement, making it easier for the reader to follow. In the supporting sentences, the writer can include examples of what kinds of writing can benefit from outlining.

Where Should I Put a Topic Sentence?

In academic writing, the topic sentence is usually the first or second sentence of a paragraph and expresses the main idea. It is followed by supporting sentences that help explain, prove, or enhance the topic sentence. In most college essays, placing an explicit topic sentence at the beginning of each paragraph (the first or second sentence) makes it easier for readers to follow the essay and for writers to stay on topic.

However, ultimately what matters is whether the reader can easily pick up on the main idea of the paragraph.  Sometimes, especially in narrative or creative writing, a writer may choose to build up to the topic sentence or even leave it implied. The following examples illustrate varying locations for the topic sentence. In each example, the topic sentence is underlined.

Topic Sentence Begins the Paragraph (General to Specific): Paragraphs that begin with the topic sentence move from the general to the specific. They open with a general statement about a subject and then discuss specific examples. This is the common pattern for most academic essays.

After reading the new TV guide this week, I wondered why we are still being bombarded with reality shows, a plague that continues to darken our airwaves. Along with the return of viewer favorites, we are to be cursed with yet another mindless creation. Prisoner follows the daily lives of eight suburban housewives who have chosen to be put in jail for the purposes of this fake psychological experiment. A preview for the first episode shows the usual tears and tantrums associated with reality television. I dread to think what producers will come up with next season and hope that other viewers will express their criticism. These producers must stop the constant stream of meaningless shows without plotlines. We’ve had enough reality television to last us a lifetime!

Here, the first sentence tells readers that the paragraph will be about reality television shows, and it expresses the writer’s distaste for these shows through the use of the word bombarded. Each of the following sentences in the paragraph supports the topic sentence by providing further information about a specific reality television show and why the writer finds it unappealing. The final sentence is the concluding sentence. It reiterates the main point that viewers are bored with reality television shows by using different words from the topic sentence.

Topic Sentence Ends the Paragraph (Specific to General): Sometimes, especially in persuasive writing, we might want to save the general statement for last when we have given enough supporting details to convince the reader.  If we build up to the topic sentence, then the reader might feel they are coming to the conclusion along with us.  The risk is that the reader will want to know sooner where the paragraph is going.

In the paragraph below, the topic sentence comes last. Specific examples, a cat that tracked down its owners and a dog that can predict seizures, prepare us for the general conclusion: animals’ senses are better than humans’.

Last year, a cat traveled 130 miles to reach its family, who had moved to another state and had left their pet behind. Even though it had never been to their new home, the cat was able to track down its former owners. A dog in my neighborhood can predict when its master is about to have a seizure. It makes sure that he does not hurt himself during an epileptic fit. Compared to many animals, our own senses are almost dull.

Topic Sentence in the Middle of the Paragraph: Occasionally, a writer might choose to hook the reader or introduce a concept before giving the topic sentence in the middle of the paragraph. In the paragraph below, the underlined topic sentence expresses the main idea—that breathing exercises can help control anxiety. The preceding sentences enable the writer to build up to their main point by using a personal anecdote. The supporting sentences then expand on how breathing exercises help the writer by providing additional information. The concluding sentence restates how breathing can help manage anxiety.

For many years, I suffered from severe anxiety every time I took an exam. Hours before the exam, my heart would begin pounding, my legs would shake, and sometimes I would become physically unable to move. Last year, I was referred to a specialist and finally found a way to control my anxiety—breathing exercises. It seems so simple, but by doing just a few breathing exercises a couple of hours before an exam, I gradually got my anxiety under control. The exercises help slow my heart rate and make me feel less anxious. Better yet, they require no pills, no equipment, and very little time. It’s amazing how just breathing correctly has helped me learn to manage my anxiety symptoms.



If you notice that you have used a topic sentence in the middle of a paragraph in an academic essay, read through the paragraph carefully to make sure that it contains only one major topic.

Implied Topic Sentences: Some well-organized paragraphs do not contain a topic sentence at all, a technique often used in descriptive and narrative writing. Instead of being directly stated, the main idea is implied in the content of the paragraph, as in the following narrative paragraph:

Heaving herself up the stairs, Luella had to pause for breath several times. She let out a wheeze as she sat down heavily in the wooden rocking chair. Tao approached her cautiously as if she might crumble at the slightest touch. He studied her face, like parchment, stretched across the bones so finely he could almost see right through the skin to the decaying muscle underneath. Luella smiled a toothless grin.

Although no single sentence in this paragraph states the main idea, the entire paragraph focuses on one concept—that Luella is extremely old. All the details in the paragraph can work together to convey the dominant impression of Luella’s age. In a paragraph such as this one, an explicit topic sentence such as “Luella was very old” would seem awkward and heavy-handed. Implied topic sentences work well if the writer has a firm idea of what they intend to say in the paragraph and sticks to it. One risk is that an implied topic sentence may be too subtle for the reader to catch.

Works Cited

Some sections of the above are original content by Anna Mills and others are adapted from the following sources:

Writing for Success, created by an author and publisher who prefer to remain anonymous, adapted and presented by the Saylor Foundation and licensed CC BY-NC-SA 3.0.

Successful College Composition, also licensed CC BY-NC-SA 3.0, which was itself adapted from Writing for Success.



“Topic Sentences” is adapted from “12.2: Topic Sentences ” of How Arguments Work – A Guide to Writing and Analyzing Texts in College (Mills), 2020, used according to creative commons  CC BY-NC-SA 4.0.



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