Dashboard
Order now
Topic sentence is the sentence that tells your reader what one paragraph in the body of an essay will cover. It usually comes first and names the single idea the rest of the paragraph has to back up. Everything after it explains, supports, or proves that idea.
Without one, your reader has to finish the paragraph before working out what it was about. That’s why each paragraph in the body of an essay gets its own.
A topic sentence helps you as much as it helps your reader. If a sentence in the paragraph doesn’t support the opening idea, it belongs somewhere else.
One sentence is the standard length. Make it specific enough to state your point, but short enough to read quickly.
Put it at the start of the paragraph. You can move it to second place if the paragraph opens with a short link back to the previous one.
It’s easy to mix up a topic sentence and a thesis statement, but they work at different levels. Your thesis states the main point of the whole essay, and each topic sentence states the main point of one paragraph that supports it.
So a five-paragraph essay has one thesis and three topic sentences.
By the end, you’ll be able to write topic sentences that open each paragraph clearly and show how it supports your thesis.
Table of contents
Qualities of a Good Topic Sentence
A good topic sentence does five things:
States one idea, not two or three
Supports a specific part of your thesis
Makes a claim rather than reporting a fact
Stays narrow enough for a single paragraph
Matches what the paragraph actually says.
One idea per sentence keeps the paragraph focused. If your sentence uses “and” to join two separate claims, you probably have two paragraphs.
The tie to your thesis is what makes the paragraph belong in this essay rather than a different one. Ask yourself, “Which part of my thesis does this paragraph defend?”
A claim is something a reader could disagree with. “The Nile is the longest river in Africa” is a fact, so nothing is left for the paragraph to prove.
Narrow means one paragraph is enough to cover it. If you’d need three paragraphs of evidence, the sentence is too big.
The last quality you can only test at the end, once the paragraph exists.
The difference between a weak claim and a strong one is easiest to see side by side.
Example of a Weak and a Strong Topic Sentence
Weak: Social media is very popular among teenagers today.
Strong: Late-night social media use shortens teenagers’ sleep, which leaves them less able to concentrate during the school day.
The weak version reports something no one would argue with. The strong version names a cause, an effect, and a group, so you can see at once which evidence the paragraph needs.
How to Write a Topic Sentence in 5 Steps
Write your thesis before you write any topic sentences. A topic sentence has to support a specific claim, so until you have settled the essay’s main point, a topic sentence has nothing to support.
Then count the paragraphs you need. A standard five-paragraph essay has three body paragraphs, so it needs three topic sentences, and a longer essay needs one in each of its body paragraphs.
Step 1: Review Your Thesis Statement
Start with the thesis you already have and break it into the separate claims it makes.
Give each of those claims its own paragraph in the body. If your thesis makes three claims, you need three paragraphs, and each topic sentence names the claim its paragraph defends.
The thesis below makes three separate claims about social media use.
Example of a Thesis on Social Media Use
Although social media helps teenagers stay in contact with their friends, heavy late-night use shortens their sleep, weakens their concentration at school, and increases how often they compare themselves with unrealistic images of their peers.
Sleep, concentration, and comparison are the three claims, so this essay needs three body paragraphs. Each one opens with a topic sentence that names its own claim.
Step 2: State the Paragraph's Main Point
Now decide what single idea this paragraph will prove.
Look at the evidence you gathered for it and ask yourself, “What do all of these examples have in common?” The answer, written as a statement rather than a question, is your topic sentence.
If the answer takes two sentences, the paragraph covers two ideas and you should split it.
Quick Tip
Test the claim against the paragraph you plan to write. If supporting it would take more than one paragraph, narrow it until one paragraph is enough.
The sentence below states one such claim about remote work.
Example of a Topic Sentence on Remote Work
Remote work returns to employees the hours they once spent commuting, and most of them use that time either for uninterrupted work or for rest.
That’s one claim, so it fits one paragraph. The evidence that follows only has to show what employees do with the extra time.
Step 3: Add a Controlling Idea
A claim names your subject. The controlling idea narrows it to the one thing you will say about that subject.
Controlling idea is the part of a topic sentence that says what you will argue about your subject. It sets the limits of the paragraph by naming the single point your evidence has to support. Without one, a topic sentence gives the reader a subject but promises nothing.
The controlling idea also tells the reader what kind of support is coming. A sentence that calls carbon pricing “unpopular” promises reasons, while one that calls it “faster than the alternatives” promises a comparison.
In the sentence below, the subject is carbon pricing and the controlling idea is everything that follows it.
Example of a Controlling Idea in a Topic Sentence
Carbon pricing reduces industrial emissions more reliably than voluntary pledges, because it changes the cost of polluting instead of relying on companies to act on their own.
The paragraph now has to show that carbon pricing works more reliably, and explain why the change in cost is the reason.
Step 4: Open with a Transition
A topic sentence can do two jobs at once. It states the paragraph’s point, and it shows the reader how that point follows from the paragraph before.
Name the idea you’re leaving before you name the one you’re starting. The link then sits inside the sentence, so you don’t need a separate signpost.
A few plain words do most of this work:
“However” and “although,” when the new paragraph contrasts with the last one
“Also” and “another,” when it adds a similar point
“Because” and “since,” when it explains a cause
“Once” and “after,” when it moves the argument forward in time.
The two openings below say the same thing about wind power, but only one of them connects to the paragraph before it.
Example of Two Topic Sentence Openings on Renewable Energy
Without a link: Wind power now supplies a growing share of household electricity across northern Europe.
With a link: Although solar panels attract most of the public attention, wind power now supplies a growing share of household electricity across northern Europe.
The second version states the same claim and also tells the reader that the essay has moved from solar power to wind.
Step 5: Check It Against the Paragraph
Once you have written the paragraph, read it again with the topic sentence in front of you.
Check every sentence against the claim. If a sentence doesn’t explain it, support it, or limit it, cut that sentence or move it to a paragraph where it fits.
Sometimes the paragraph is fine and the opening is wrong. When most of your evidence points somewhere the topic sentence never promised, rewrite the topic sentence to match what you actually wrote.
The revision below started as a claim about traffic and ended as a claim the paragraph could support.
Example of a Revised Topic Sentence on Urban Transport
Original: Traffic is a serious problem in most large cities.
Revised: Cities that widen bus lanes instead of adding road capacity cut peak-hour congestion within two years, because commuters switch to whichever option is faster.
The original names a subject and stops there. The revised version names a subject, a claim, and a reason, so you can test every sentence in the paragraph against it.
Topic Sentence Examples and Ideas
Topic sentences look different depending on what the essay is doing. The samples below cover four common types: argumentative, expository, compare-and-contrast, and narrative.
Example Topic Sentences for Four Essay Types
Argumentative: School districts should push high school start times back to 8:30 a.m., because students who sleep longer attend more classes and fail fewer of them.
Expository: The water cycle moves water between the ocean, the atmosphere, and the land through four stages: evaporation, condensation, precipitation, and collection.
Compare-and-contrast: Online and in-person courses can cover the same material, but they place very different demands on a student’s time management.
Narrative: The morning I missed the school bus taught me more about planning than any lesson that year.
You can reuse these shapes with your own subject. The starting points below fit most assignments:
An effect of your topic that most readers overlook
A comparison between two options your reader already knows
The reason a popular solution doesn’t work
A change over time that your evidence can show
An exception to a rule you have just described.
Common Topic Sentence Mistakes
Five problems account for most weak topic sentences:
Stating a fact instead of a claim
Announcing the paragraph instead of opening it
Joining two claims with “and”
Repeating the thesis word for word
Making a claim the paragraph is too short to support.
A fact gives the paragraph nothing to prove. Turn it into something a reader could disagree with, then use the fact as evidence inside the paragraph.
Announcing sounds like “This paragraph will discuss school start times.” Delete the announcement and state the point instead.
Two claims joined by “and” usually means two paragraphs. Keep the one you have more evidence for and move the other.
Repeating the thesis wastes the sentence. Point to the one part of the argument that this paragraph handles.
A claim that’s too big won’t fit in one paragraph. Narrow it until the evidence you have is enough.
Students often ask whether the sentence can be a question instead.
Note
A question can open a paragraph, but it doesn’t state the paragraph’s point, so it isn’t doing the work of a topic sentence. If you want to use one, answer it in the very next sentence and treat that answer as your real topic sentence.
Final Thoughts on Topic Sentences
A paragraph that opens with a clear claim is easier to write and easier to read. You know what belongs in it, and your reader knows what’s coming.
Get the topic sentences right and the rest of each paragraph is mostly a matter of arranging the evidence you already have.
Quick Tip
Read your thesis and your topic sentences on their own, in order, and nothing else. If they still state the argument of your essay, your paragraphs are where they should be.