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  • How to Write Topic Sentences | 4 Steps, Examples & Purpose

How to Write Topic Sentences | 4 Steps, Examples & Purpose

Published on July 21, 2022 by Shona McCombes . Revised on June 5, 2023.

How to Write Topic Sentences

Every paragraph in your paper needs a topic sentence . The topic sentence expresses what the paragraph is about. It should include two key things:

  • The  topic of the paragraph
  • The central point of the paragraph.

After the topic sentence, you expand on the point zwith evidence and examples.

To build a well-structured argument, you can also use your topic sentences to transition smoothly between paragraphs and show the connections between your points.

Table of contents

Writing strong topic sentences, topic sentences as transitions between paragraphs, topic sentences that introduce more than one paragraph, where does the topic sentence go, frequently asked questions about topic sentences.

Topic sentences aren’t the first or the last thing you write—you’ll develop them throughout the writing process. To make sure every topic sentence and paragraph serves your argument, follow these steps.

Step 1: Write a thesis statement

The first step to developing your topic sentences is to make sure you have a strong thesis statement . The thesis statement sums up the purpose and argument of the whole paper.

Thesis statement example

Food is an increasingly urgent environmental issue, and to reduce humans’ impact on the planet, it is necessary to change global patterns of food production and consumption.

Step 2: Make an essay outline and draft topic sentences

Next, you should make an outline of your essay’s structure , planning what you want to say in each paragraph and what evidence you’ll use.

At this stage, you can draft a topic sentence that sums up the main point you want to make in each paragraph. The topic sentences should be more specific than the thesis statement, but always clearly related to it.

Topic sentence example

Research has consistently shown that the meat industry has a significant environmental impact .

Step 3: Expand with evidence

The rest of the paragraph should flow logically from the topic sentence, expanding on the point with evidence, examples, or argumentation. This helps keep your paragraphs focused: everything you write should relate to the central idea expressed in the topic sentence.

In our example, you might mention specific research studies and statistics that support your point about the overall impact of the meat industry.

Step 4: Refine your topic sentences

Topic sentences usually start out as simple statements. But it’s important to revise them as you write, making sure they match the content of each paragraph.

A good topic sentence is specific enough to give a clear sense of what to expect from the paragraph, but general enough that it doesn’t give everything away. You can think of it like a signpost: it should tell the reader which direction your argument is going in.

To make your writing stronger and ensure the connections between your paragraphs are clear and logical, you can also use topic sentences to create smooth transitions. To improve sentence flow even more, you can also utilize the paraphrase tool .

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As you write each topic sentence, ask yourself: how does this point relate to what you wrote in the preceding paragraph? It’s often helpful to use transition words in your topic sentences to show the connections between your ideas.

Emphasize and expand

If the paragraph goes into more detail or gives another example to make the same point, the topic sentence can use words that imply emphasis or similarity (for example, furthermore , indeed , in fact , also ).

Indeed , cattle farming alone is responsible for a large proportion of greenhouse gas emissions.

Summarize and anticipate

If the paragraph turns to a different aspect of the same subject, the topic sentence can briefly sum up the previous paragraph and anticipate the new information that will appear in this one.

While beef clearly has the most dramatic footprint, other animal products also have serious impacts in terms of emissions, water and land use.

Compare and contrast

If the paragraph makes a comparison or introduces contrasting information, the topic sentence can use words that highlight difference or conflict (for example, in contrast , however , yet , on the other hand ).

However , the environmental costs of dietary choices are not always clear-cut; in some cases, small-scale livestock farming is more sustainable than plant-based food production.

You can also imply contrast or complicate your argument by formulating the topic sentence as a question.

Is veganism the only solution, or are there more sustainable ways of producing meat and dairy?

Sometimes you can use a topic sentence to introduce several paragraphs at once.

All of the examples above address the environmental impact of meat-eating versus veganism. Together, they make up one coherent part of a larger argument, so the first paragraph could use a topic sentence to introduce the whole section.

In countries with high levels of meat consumption, a move towards plant-based diets is the most obvious route to making food more sustainable. Research has consistently shown that the meat industry has significant environmental impacts.

The topic sentence usually goes at the very start of a paragraph, but sometimes it can come later to indicate a change of direction in the paragraph’s argument.

Given this evidence of the meat industry’s impact on the planet, veganism seems like the only environmentally responsible option for consumers. However, the environmental costs of dietary choices are not always clear-cut; in some cases, small-scale livestock farming is more sustainable than plant-based food production.

In this example, the first sentence summarizes the main point that has been made so far. Then the topic sentence indicates that this paragraph will address evidence that complicates or contradicts that point.

In more advanced or creative forms of academic writing , you can play with the placement of topic sentences to build suspense and give your arguments more force. But if in doubt, to keep your research paper clear and focused, the easiest method is to place the topic sentence at the start of the paragraph.

View topic sentences in an example essay

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A topic sentence is a sentence that expresses the main point of a paragraph . Everything else in the paragraph should relate to the topic sentence.

Topic sentences help keep your writing focused and guide the reader through your argument.

In an essay or paper , each paragraph should focus on a single idea. By stating the main idea in the topic sentence, you clarify what the paragraph is about for both yourself and your reader.

The topic sentence usually comes at the very start of the paragraph .

However, sometimes you might start with a transition sentence to summarize what was discussed in previous paragraphs, followed by the topic sentence that expresses the focus of the current paragraph.

Let’s say you’re writing a five-paragraph  essay about the environmental impacts of dietary choices. Here are three examples of topic sentences you could use for each of the three body paragraphs :

  • Research has shown that the meat industry has severe environmental impacts.
  • However, many plant-based foods are also produced in environmentally damaging ways.
  • It’s important to consider not only what type of diet we eat, but where our food comes from and how it is produced.

Each of these sentences expresses one main idea – by listing them in order, we can see the overall structure of the essay at a glance. Each paragraph will expand on the topic sentence with relevant detail, evidence, and arguments.

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Topic Sentence

Every paragraph should include a topic sentence that identifies the main idea of the paragraph. A topic sentence also states the point the writer wishes to make about that subject. Generally, the topic sentence appears at the beginning of the paragraph. It is often the paragraph’s very first sentence. A paragraph’s topic sentence must be general enough to express the paragraph’s overall subject. However, it should be specific enough that the reader can understand the paragraph’s main subject and point.

  • The topic sentence should identify the main idea and point of the paragraph. To choose an appropriate topic sentence, read the paragraph and think about its main idea and point.
  • The supporting details in the paragraph (the sentences other than the topic sentence) will develop or explain the topic sentence. Read all the supporting details in the paragraph and think about the ideas they discuss.
  • The topic sentence should not be too general or too specific. When considering the options, look for a topic sentence that is general enough to show the paragraph’s main idea instead of just one of its details. The answer should be specific enough that the reader understands the main idea of the paragraph.

More About the Topic Sentence

A topic sentence is the most important sentence in a paragraph. Sometimes referred to as a focus sentence, the topic sentence helps organize the paragraph by summarizing the information in the paragraph. In academic writing, the topic sentence is usually the first sentence in a paragraph (although it does not have to be).

Purpose of the Topic Sentence

A topic sentence essentially tells readers about the rest of the paragraph. All sentences after it have to give more information about that sentence, prove it by offering facts about it, or describe it in more detail. For example, if the topic sentence concerns the types of endangered species that live in the ocean, then every sentence after that needs to expands on that subject.

Topic sentences also need to relate back to the thesis of the essay. The thesis statement is like a road map that will tell the reader or listener where you are going with this information or how you are treating it.

Topic Sentences and Controlling Ideas

Every topic sentence will have a topic and a controlling idea. The controlling idea shows the direction the paragraph will take.

Examples of a Topic Sentence

Topic Sentence: There are many reasons why pollution in ABC Town is the worst in the world.

The topic is "pollution in ABC Town is the worst in the world" and the controlling idea is "many reasons."

Topic Sentence: To be an effective CEO requires certain characteristics.

The topic is "To be an effective CEO" and the controlling idea is "certain charactristics."

Topic Sentence: There are many possible contributing factors to global warming.

The topic is "global warming" and the controlling idea is "contributing factors."

Topic Sentence: Fortune hunters encounter many difficulties when exploring a shipwreck.

The topic is "exploring a shipwreck" and the controlling idea is "many difficulties."

Topic Sentence: Dogs make wonderful pets because they help you to live longer.

The topic is "dogs make wonderful pets" and the controlling idea is "because they help you

to live longer."

Topic Sentence: Crime in poverty-stricken areas occurs because of a systemic discrimination.

The topic is "crime in poverty stricken areas" and the controlling idea is "systemic discrimination."

Topic Sentence: Teen pregnancy may be prevented by improved education.

The topic is "teen pregnancy may be prevented" and the controlling idea is "improved education."

Topic Sentence: Cooking requires a number of different skills.

The topic is "cooking" and the controlling idea is "many different skills."

Topic Sentence: It is important to be ready before buying a house.

The topic is "buying a house" and the controlling idea is “it is important to be ready."

Topic Sentence: Graduating from high school is important for many different reasons.

The topic is "graduating from high school" and the controlling idea is "many different reasons."

Topic Sentence: Having a first child is difficult because of the significant adjustments in your life.

The topic is "having a first child" and the controlling idea is "significant adjustments in your life."

Topic Sentence: Remodeling a kitchen successfully requires research and a good eye.

The topic is "remodeling a kitchen" and the controlling idea is "requires research and a good eye."

Topic Sentence Exercise

Write a topic sentence for the following paragraph. During the 1990s, I really enjoyed watching Friends on television every Thursday night. I really wanted Rachel’s haircut—I think every girl wanted Rachel’s haircut back then! Rachel’s haircut went really well with the Guess Jeans that were so popular in the 1990s. I remember all the advertisements for Guess and Calvin Klein Jeans that were in each month’s Sassy magazine. I do not think Sassy magazine exists anymore, but it was one of the most popular magazines for young women in the 1990s.

Topic Sentences Exercise Answer

The bold sentence is one possible topic sentence for the example paragraph.

Note: This is just one possible topic sentence—you may have thought of others that are also appropriate.

Thinking about the 1990s brings back fond memories for me about fashion and popular culture. During the 1990s, I really enjoyed watching Friends on television every Thursday night. I really wanted Rachel’s haircut—I think every girl wanted Rachel’s haircut back then! Rachel’s haircut went really well with the Guess Jeans that were so popular in the 1990s. I remember all the advertisements for Guess and Calvin Klein Jeans that were in each month’s Sassy magazine. I do not think Sassy magazine exists anymore, but it was one of the most popular magazines for young women in the 1990s.

*Source: Purdue OWL


What Is a Topic Sentence?

  • An Introduction to Punctuation
  • Ph.D., Rhetoric and English, University of Georgia
  • M.A., Modern English and American Literature, University of Leicester
  • B.A., English, State University of New York

A topic sentence is a  sentence , sometimes at the beginning of a paragraph , that states or suggests the main idea (or topic ) of a paragraph.

Not all paragraphs begin with topic sentences. In some, the topic sentence appears in the middle or at the end. In others, the topic sentence is implied or absent altogether.

Examples and Observations

  • " Salva and the other boys made cows out of clay. The more cows you made, the richer you were. But they had to be fine, healthy animals. It took time to make a lump of clay look like a good cow. The boys would challenge each other to see who could make the most and best cows." (Linda Sue Park, A Long Walk to Water . Clarion, 2010)
  • " Momma bought two bolts of cloth each year for winter and summer clothes. She made my school dresses, underslips, bloomers, handkerchiefs, Bailey's shirts, shorts, her aprons, house dresses and waists from the rolls shipped to Stamps by Sears and Roebuck. . . ." (Maya Angelou, I Know Why the Caged Bird Sings . Random House, 1969)
  • " You discover what it is like to be hungry. With bread and margarine in your belly, you go out and look into the shop windows. Everywhere there is food insulting you in huge, wasteful piles; whole dead pigs, baskets of hot loaves, great yellow blocks of butter, strings of sausages, mountains of potatoes, vast Gruyère cheeses like grindstones. A snivelling self-pity comes over you at the sight of so much food. You plan to grab a loaf and run, swallowing it before they catch you; and you refrain, from pure funk." (George Orwell, Down and Out in Paris and London . Victor Gollancz, 1933)
  • " The flavor that salt imparts to food is just one of the attributes that manufacturers rely on. For them, salt is nothing less than a miracle worker in processed foods. It makes sugar taste sweeter. It adds crunch to crackers and frozen waffles. It delays spoilage so that the products can sit longer on the shelf. And, just as importantly, it masks the otherwise bitter or dull taste that hounds so many processed foods before salt is added." (Michael Moss, Salt, Sugar, Fat: How the Food Giants Hooked Us . Random House, 2013)
  • " The very idea of retirement is a relatively new invention. For most of human history, people worked until they died or were too infirm to lift a finger (at which point they died pretty fast anyway). It was the German statesman Otto von Bismarck who first floated the concept, in 1883, when he proposed that his unemployed countrymen over the age of 65 be given a pension. This move was designed to fend off Marxist agitation—and to do so on the cheap, since few Germans survived to that ripe old age." (Jessica Bruder, "The End of Retirement." Harper's , August 2014)
  • " Grandma's room I regarded as a dark den of primitive rites and practices. On Friday evenings whoever was home gathered at her door while she lit her Sabbath candles. . . ."  (E.L. Doctorow, World's Fair . Random House, 1985)
  • " Genealogy is an ancient human preoccupation. The God of Hebrew Scripture promised Abraham descendants beyond number, like the stars in the sky and the sand on the seashore. The apostles Matthew and Luke claim that Abraham's lineage went on to include King David and eventually Jesus, though the specifics of their accounts are contradictory. Muslims trace Mohammed's line back through Abraham, to Adam and Eve." (Maud Newton, "America's Ancestry Craze." Harper's , June 2014)
  • " O nce, in a restaurant in Italy with my family, I occasioned enormous merriment, as a nineteenth-century humorist would have put it, by confusing two Italian words. I thought I had, very suavely, ordered for dessert fragoline —those lovely little wild strawberries. Instead, I seem to have asked for fagiolini —green beans. The waiter ceremoniously brought me a plate of green beans with my coffee, along with the flan and the gelato for the kids. The significant insight the mistake provided—arriving mere microseconds after the laughter of those kids, who for some reason still bring up the occasion, often—was about the arbitrary nature of language: the single 'r' rolled right makes one a master of the trattoria, an 'r' unrolled the family fool. . . ." (Adam Gopnik, "Word Magic." The New Yorker , May 26, 2014)
  • " In seventeenth-century Europe, the transformation of man into soldier took on a new form, more concerted and disciplined, and far less pleasant, than wine. New recruits and even seasoned veterans were endlessly drilled, hour after hour, until each man began to feel himself part of a single, giant fighting machine. . . ." (Barbara Ehrenreich, Blood Rites: Origins and History of the Passions of War . Henry Holt and Company, 1997)
  • " What is the appeal of train travel? Ask almost any foamer, and he or she will invariably answer, 'The romance of it!' But just what this means, they cannot really say. It's tempting to think that we are simply equating romance with pleasure, with the superior comfort of a train, especially seated up high in the observation cars. . . ." (Kevin Baker, "21st Century Limited: The Lost Glory of America's Railroads." Harper's , July 2014)
  • " Because science fiction spans the spectrum from the plausible to the fanciful, its relationship with science has been both nurturing and contentious. For every author who meticulously examines the latest developments in physics or computing, there are other authors who invent 'impossible' technology to serve as a plot device (like Le Guin’s faster-than-light communicator, the ansible) or to enable social commentary, the way H. G. Wells uses his time machine to take the reader to the far future to witness the calamitous destiny of the human race." (Eileen Gunn, "Brave New Words." Smithsonian , May 2014)
  • " I passed all the other courses that I took at my university, but I could never pass botany. . . ." (James Thurber, My Life and Hard Times . Harper & Row, 1933)
  • " What is there about this wonderful woman? From next door, she comes striding, down the lawn, beneath the clothesline, laden with cookies she has just baked, or with baby togs she no longer needs, and one's heart goes out. Pops out. The clothesline, the rusted swing set, the limbs of the dying elm, the lilacs past bloom are lit up like rods of neon by her casual washday energy and cheer, a cheer one has done nothing to infuse." (John Updike, "One's Neighbor's Wife." Hugging the Shore: Essays and Criticism . Knopf, 1983)
  • " Television. Why do I watch it? The parade of politicians every evening: I have only to see the heavy, blank faces so familiar since childhood to feel gloom and nausea. . . ." (J.M. Coetzee, Age of Iron . Random House, 1990)
  • " Anyone who has made the coast-to-coast journey across America, whether by train or by car, has probably passed through Garden City, but it is reasonable to assume that few travelers remember the event. It seems just another fair-sized town in the middle--almost the exact middle--of the continental United States. . . ." (Truman Capote, In Cold Blood . Random House, 1966)
  • " Rodeo, like baseball, is an American sport and has been around almost as long. . . ." (Gretel Ehrlich, The Solace of Open Spaces . Viking Penguin, 1985)
  • " What a piece of work is a book! I am not talking about writing or printing. I am talking about the codex we may leaf through, that may be put away on a shelf for whole centuries and will remain there, unchanged and handy. . . ." (William Golding, A Moving Target . Farrar, Straus and Giroux, 1982)

Characteristics of an Effective Topic Sentence

  • "A good topic sentence is concise and emphatic . It is no longer than the idea requires, and it stresses the important word or phrase. Here, for instance, is the topic sentence which opens a paragraph about the collapse of the stock market in 1929: "The Bull Market was dead."(Frederick Lewis Allen) Notice several things. (1) Allen's sentence is brief . Not all topics can be explained in six words, but whether they take six or sixty, they should be phrased in no more words than are absolutely necessary. (2) The sentence is clear and strong: you understand exactly what Allen means. (3) It places the keyword—'dead'—at the end, where it gets heavy stress and leads naturally into what will follow. . . . (4) The sentence stands first in the paragraph. This is where topic sentences generally belong: at or near the beginning." (Thomas S. Kane, The New Oxford Guide to Writing . Oxford Univ. Press, 1988)

Positioning a Topic Sentence

"If you want readers to see your point immediately, open with the topic sentence . This strategy can be particularly useful in letters of application or in argumentative writing. . . . "When specific details lead up to a generalization, putting the topic sentence at the end of the paragraph makes sense. . . . "Occasionally a paragraph's main idea is so obvious that it does not need to be stated explicitly in a topic sentence." (Andrea Lunsford, The St. Martin's Handbook . Bedford/St. Martin's, 2008)

Guidelines for Composing Topic Sentences

"The topic sentence is the most important sentence in your paragraph. Carefully worded and restricted, it helps you generate and control your information. An effective topic sentence also helps readers grasp your main idea quickly. As you draft your paragraphs, pay close attention to the following three guidelines:

  • Make sure you provide a topic sentence. . . .
  • Put your topic sentence first.
  • Be sure your topic sentence is focused. If restricted, a topic sentence discusses only one central idea. A broad or unrestricted topic sentence leads to a shaky, incomplete paragraph for two reasons:
  • The paragraph will not contain enough information to support the topic sentence .
  • A broad topic sentence will not summarize or forecast specific information in the paragraph."

(Philip C. Kolin, Successful Writing at Work , 9th ed. Wadsworth, 2010)

Testing for Topic Sentences

"When testing your article for topic sentences , you should be able to look at each paragraph and say what the topic sentence is. Having said it, look at all the other sentences in the paragraph and test them to make sure they support it. . . .

"If you find that you have come up with the same topic sentence more than once, you have two paragraphs doing the same work. Cut one of them out.

"If you find a paragraph that has several sentences that don't support the topic sentence, see if all the outlaw sentences support some other topic sentence and turn the one paragraph into two." (Gary Provost, "How to Test Your Articles for the 8 Essentials of Nonfiction." Handbook of Magazine Article Writing , ed. by Jean M. Fredette. Writer's Digest Books, 1988)

Frequency of Topic Sentences

"Teachers and textbook writers should exercise caution in making statements about the frequency with which contemporary professional writers use simple or even explicit topic sentences in expository paragraphs. It is abundantly clear that students should not be told that professional writers usually begin their paragraphs with topic sentences."  (Richard Braddock, "The Frequency and Placement of Topic Sentences in Expository Prose." Research in the Teaching of English . Winter 1974)

  • How to Teach Topic Sentences Using Models
  • Practice in Supporting a Topic Sentence with Specific Details
  • Unity in Composition
  • What Is Expository Writing?
  • Paragraph Writing
  • Development in Composition: Building an Essay
  • Definition and Examples of Body Paragraphs in Composition
  • How to Write a Descriptive Paragraph
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  • Writers on Writing: The Art of Paragraphing
  • Definition and Examples of Analysis in Composition
  • Supporting Detail in Composition and Speech
  • How to Structure an Essay
  • Definition and Examples of Paragraphing in Essays
  • Topic In Composition and Speech

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The Topic Sentence

The "topic sentence" is the sentence in which the main idea of the paragraph is stated. It is unquestionably the most important sentence in the paragraph. The topic sentence generally is composed of two parts: (a) the topic itself and (b) the controlling idea.

The topic is the subject of the paragraph. It is what the paragraph is all about. The following are topics suitable for a paragraph:

The SLR camera Vegetarianism Tokyo Pottery A wedding cake

Writing effective topic sentences, however, involves more than merely stating the subject of the paragraph. A good topic sentence is specific and well focused, guiding the entire paragraph. A good topic sentence:

Has new information. It is not a fact that everyone already knows to be true (for example, A dictionary has meanings for words. ). Is specific. If the topic is too general (for example, I like camping. ), the reader will not know what to expect in the paragraph. Is general enough to invite exploration of the topic. If the topic sentence is too specific (for example, Webster's New World Dictionary has more than 40,000 words. ), there will be nothing else to say on the subject. Is strong. Starting a topic sentence with there is/are (as in There are several ways to cook rice. ) is a weak opener. Is stated in positive language. Negative language (for example, You might hate to do it, but you should keep your room clean. ) should not be part of the topic sentence. Is not an announcement. A topic sentence should draw the reader into the paragraph. Announcements (like This paragraph will discuss how to build a bird house. ) hold little attraction for readers.

The Controlling Idea

Even if all of the above conditions for a topic sentence are met, an effective topic sentence needs one additional element, the "controlling idea." The controlling idea is the point of the paragraph. It guides the ideas that provide support for the paragraph and limits the scope of the paragraph. Here is an example of a topic sentence with a controlling idea that guides the support for the paragraph:

Running provides many healthful benefits.

The topic of this topic sentence is running . The controlling idea is healthful benefits . That is, the reader knows from this sentence that the paragraph is generally about running. And the reader also knows that the point of the paragraph will be to enumerate the healthful benefits of running. Limiting the scope of the paragraph through the controlling idea may happen in one of two ways.

1. The controlling idea may reveal the writer's opinion, point of view, or attitude toward the subject of the paragraph, which automatically will set parameters for discussion of the topic. OR…

2. The controlling idea itself may provide specific limitation. In either case, this limited scope, then, serves to unify the paragraph, since any discussion must be within the parameters of the controlling idea.

Here is an example of a topic sentence with a controlling idea that states the writer's opinion-the first way to limit the scope of the paragraph:

The basics of using an SLR camera can be mastered with considerable practice.

The topic of this sentence is an SLR camera . The controlling idea is mastered with considerable practice . From this single sentence the reader knows that the topic of the paragraph is the SLR camera and that the paragraph will discuss mastering the basics of using this camera. Additionally, the reader knows that such mastery comes with practice, the writer's opinion or perspective.

Here is an example of a topic sentence with a controlling idea that specifically sets limitations for the scope of the paragraph.

When writing a laboratory report, you must complete four sections.

The topic of this sentence is a laboratory report . In this sentence, the controlling idea specifically states the limitation- four sections . Thus, the reader can predict that the writer will list and describe the four sections in order.

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Topic Sentence and Paragraph

What is a paragraph.

A paragraph is a group of sentences that convey an idea. Each sentence works together as part of a unit to create an overall thought or impression. A paragraph is the smallest unit or cluster of sentences in which one idea   can be developed adequately. Paragraphs can stand alone or function as part of an essay, but each paragraph covers only one main idea .

The most important sentence in your paragraph is the topic sentence , which clearly states the subject of the whole paragraph. The topic sentence is usually the first sentence of the paragraph because it gives an overview of the sentences to follow. The supporting sentences after the topic sentence help to develop the main idea. These sentences give specific details related to the topic sentence. A final or concluding sentence often restates or summarizes the main idea of the topic sentence.

Effective Paragraphs

An effective parapraph contains:

  • a topic sentence that states the main point of the paragraph
  • supporting sentences with details and specific examples as proof of your point
  • logical, coherent thoughts that are developed in order from one sentence to the next
  • a concluding idea that wraps up the point of the paragraph

Below is a paragraph model. It contains a topic sentence with concrete details and examples in the supporting sentences. Notice how the writer sums up the point of the paragraph with a concluding sentence .

Also, because this is academic writing, the writer indents the first line five spaces to mark the beginning of a paragraph. This practice is not always followed in commercial or instructive writing, or in business letters or memos.

My First Day

My first day of college was a disaster. First, I went to the wrong classroom for math. I was sitting in the class, surrounded by people taking notes and paying attention to how to do equations, which would have been okay if I was supposed to be in an algebra class. In reality, I was supposed to be in geometry, and when I discovered my error, I had already missed the first twenty minutes of a one-hour class. When I got to the correct class, all twenty-five students turned and looked at me as the teacher said, "You're late." That would have been bad enough, but in my next class my history teacher spoke so fast I could not follow most of what they said. The only thing I did hear was that we were having a quiz tomorrow over today’s lecture. My day seemed to be going better during botany class, that is, until we visited the lab. I had a sneezing fit because of one of the plants in the lab and had to leave the room. When I finally finished my classes for the day, I discovered I had locked my keys in the car and had to wait for my brother to bring another set. My first day of school was so bad that I know the rest will have to be better.

In the above paragraph, the topic sentence appears in bold and the concluding sentence in italics. The sentences in between support and develop the topic sentence by giving specific examples and details. These examples are the writer’s “proof” of their bad first day of school.

Effective Topic Sentences

An effective topic sentence:

  • informs the reader of the subject that will be discussed in the paragraph
  • asserts the writer’s point of view or attitude
  • intrigues the reader to continue reading
  • creates a sense of action
  • is not vague, rambling, too narrow or too broad
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Paragraphs & topic sentences.

A paragraph is a series of sentences that are organized and coherent, and are all related to a single topic. Almost every piece of writing you do that is longer than a few sentences should be organized into paragraphs. This is because paragraphs show a reader where the subdivisions of an essay begin and end, and thus help the reader see the organization of the essay and grasp its main points.

Paragraphs can contain many different kinds of information. A paragraph could contain a series of brief examples or a single long illustration of a general point. It might describe a place, character, or process; narrate a series of events; compare or contrast two or more things; classify items into categories; or describe causes and effects. Regardless of the kind of information they contain, all paragraphs share certain characteristics. One of the most important of these is a topic sentence.


A well-organized paragraph supports or develops a single controlling idea, which is expressed in a sentence called the topic sentence. A topic sentence has several important functions: it substantiates or supports an essay’s thesis statement; it unifies the content of a paragraph and directs the order of the sentences; and it advises the reader of the subject to be discussed and how the paragraph will discuss it. Readers generally look to the first few sentences in a paragraph to determine the subject and perspective of the paragraph. That’s why it’s often best to put the topic sentence at the very beginning of the paragraph. In some cases, however, it’s more effective to place another sentence before the topic sentence—for example, a sentence linking the current paragraph to the previous one, or one providing background information.

Although most paragraphs should have a topic sentence, there are a few situations when a paragraph might not need a topic sentence. For example, you might be able to omit a topic sentence in a paragraph that narrates a series of events, if a paragraph continues developing an idea that you introduced (with a topic sentence) in the previous paragraph, or if all the sentences and details in a paragraph clearly refer—perhaps indirectly—to a main point. The vast majority of your paragraphs, however, should have a topic sentence.


Most paragraphs in an essay have a three-part structure—introduction, body, and conclusion. You can see this structure in paragraphs whether they are narrating, describing, comparing, contrasting, or analyzing information. Each part of the paragraph plays an important role in communicating your meaning to your reader.

Introduction : the first section of a paragraph; should include the topic sentence and any other sentences at the beginning of the paragraph that give background information or provide a transition.

Body : follows the introduction; discusses the controlling idea, using facts, arguments, analysis, examples, and other information.

Conclusion : the final section; summarizes the connections between the information discussed in the body of the paragraph and the paragraph’s controlling idea.

The following paragraph illustrates this pattern of organization. In this paragraph the topic sentence and concluding sentence (CAPITALIZED) both help the reader keep the paragraph’s main point in mind.

SCIENTISTS HAVE LEARNED TO SUPPLEMENT THE SENSE OF SIGHT IN NUMEROUS WAYS. In front of the tiny pupil of the eye they put , on Mount Palomar, a great monocle 200 inches in diameter, and with it see 2000 times farther into the depths of space. Or they look through a small pair of lenses arranged as a microscope into a drop of water or blood, and magnify by as much as 2000 diameters the living creatures there, many of which are among man’s most dangerous enemies. Or , if we want to see distant happenings on earth, they use some of the previously wasted electromagnetic waves to carry television images which they re-create as light by whipping tiny crystals on a screen with electrons in a vacuum. Or they can bring happenings of long ago and far away as colored motion pictures, by arranging silver atoms and color-absorbing molecules to force light waves into the patterns of original reality. Or if we want to see into the center of a steel casting or the chest of an injured child, they send the information on a beam of penetrating short-wave X rays, and then convert it back into images we can see on a screen or photograph. THUS ALMOST EVERY TYPE OF ELECTROMAGNETIC RADIATION YET DISCOVERED HAS BEEN USED TO EXTEND OUR SENSE OF SIGHT IN SOME WAY. George Harrison, “Faith and the Scientist”

In a coherent paragraph, each sentence relates clearly to the topic sentence or controlling idea, but there is more to coherence than this. If a paragraph is coherent, each sentence flows smoothly into the next without obvious shifts or jumps. A coherent paragraph also highlights the ties between old information and new information to make the structure of ideas or arguments clear to the reader.

Along with the smooth flow of sentences, a paragraph’s coherence may also be related to its length. If you have written a very long paragraph, one that fills a double-spaced typed page, for example, you should check it carefully to see if it should start a new paragraph where the original paragraph wanders from its controlling idea. On the other hand, if a paragraph is very short (only one or two sentences, perhaps), you may need to develop its controlling idea more thoroughly, or combine it with another paragraph.

A number of other techniques that you can use to establish coherence in paragraphs are described below.

Repeat key words or phrases. Particularly in paragraphs in which you define or identify an important idea or theory, be consistent in how you refer to it. This consistency and repetition will bind the paragraph together and help your reader understand your definition or description.

Create parallel structures. Parallel structures are created by constructing two or more phrases or sentences that have the same grammatical structure and use the same parts of speech. By creating parallel structures you make your sentences clearer and easier to read. In addition, repeating a pattern in a series of consecutive sentences helps your reader see the connections between ideas. In the paragraph above about scientists and the sense of sight, several sentences in the body of the paragraph have been constructed in a parallel way. The parallel structures (which have been emphasized ) help the reader see that the paragraph is organized as a set of examples of a general statement.

Be consistent in point of view, verb tense, and number. Consistency in point of view, verb tense, and number is a subtle but important aspect of coherence. If you shift from the more personal "you" to the impersonal “one,” from past to present tense, or from “a man” to “they,” for example, you make your paragraph less coherent. Such inconsistencies can also confuse your reader and make your argument more difficult to follow.

Use transition words or phrases between sentences and between paragraphs. Transitional expressions emphasize the relationships between ideas, so they help readers follow your train of thought or see connections that they might otherwise miss or misunderstand. The following paragraph shows how carefully chosen transitions (CAPITALIZED) lead the reader smoothly from the introduction to the conclusion of the paragraph.

I don’t wish to deny that the flattened, minuscule head of the large-bodied "stegosaurus" houses little brain from our subjective, top-heavy perspective, BUT I do wish to assert that we should not expect more of the beast. FIRST OF ALL, large animals have relatively smaller brains than related, small animals. The correlation of brain size with body size among kindred animals (all reptiles, all mammals, FOR EXAMPLE) is remarkably regular. AS we move from small to large animals, from mice to elephants or small lizards to Komodo dragons, brain size increases, BUT not so fast as body size. IN OTHER WORDS, bodies grow faster than brains, AND large animals have low ratios of brain weight to body weight. IN FACT, brains grow only about two-thirds as fast as bodies. SINCE we have no reason to believe that large animals are consistently stupider than their smaller relatives, we must conclude that large animals require relatively less brain to do as well as smaller animals. IF we do not recognize this relationship, we are likely to underestimate the mental power of very large animals, dinosaurs in particular. Stephen Jay Gould, “Were Dinosaurs Dumb?”


(modified from Diana Hacker, A Writer’s Reference )

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Module 3: Writing Essentials

Topic sentences, learning objectives.

  • Identify topic sentences in paragraphs

Empty flow chart.

Figure 1 . A nicely constructed topic sentence will help the reader to better understand the flow of an essay.

Key Sentences

In academic writing, readers expect each paragraph to have a sentence or two that captures its main point. They’re often called topic sentences , though some writing instructors call them “key sentences.” The phrase “topic sentence” could be misleading, because it makes it seem like it always announces the topic of a paragraph or that it is always one sentence. That may not always be true. Calling them a topic topic or a key sentence reminds us that it expresses the central idea of the paragraph.

Topic sentences in academic writing do two things. First, they establish the main point that the rest of the paragraph supports. Second, they situate each paragraph within the sequence of the argument, a task that requires transitioning from the prior paragraph.

Consider the following examples about about epidemiological and etiological evidence. If you are unfamiliar with these terms, epidemiological evidence is related to the study of diseases. Etiological studies refer to the study of the origin of a disease.

Version A: Now we turn to the epidemiological evidence. Version B: If the evidence emerging from etiological studies supports the hypothesis, the epidemiological evidence is also compelling.

Both versions convey a topic; it’s pretty easy to predict that the paragraph will be about epidemiological evidence, but only the second version establishes an argumentative point and puts it in context. The paragraph doesn’t just describe the epidemiological evidence; it shows how epidemiology is telling the same story as etiology. Similarly, while Version A doesn’t relate to anything in particular, Version B immediately suggests that the prior paragraph addresses the biological pathway (i.e., etiology) of a disease and that the new paragraph will bolster the emerging hypothesis with a different kind of evidence (epidemiological). The topic or key sentences make it easy for the reader to keep track of how the essay moves from one paragraph and idea to the next.

Try It: Topic sentences

Read the paragraph about camera flash technology and answer the question below:

When a camera flash is used in a low-light environment, the subject’s eyes may appear red in the finished photograph. What is known as “red-eye” is the result of light from the flash reflecting off the pupils of the eyes. The phenomenon of red-eye can be lessened by using the red-eye reduction feature found on many SLR cameras. This feature activates a lamp that shines a small light directly into the subject’s eyes. When this happens, the diameter of the pupil is reduced, thus tightening the opening in the iris. Since a smaller pupil means a smaller host for the reflection, the chances of red-eye occurring are greatly reduced.

Topic sentences have a topic and an angle or claim, just like thesis sentences. But the angle of topic sentences usually is smaller in range than that of the thesis sentence. Very often the topic remains the same from thesis to topic sentence, while the angle shifts as the writer brings in various types of ideas and research to support the angle in the thesis.

Look at this sample below; these are topic sentences created from the thesis sentence. The topic remains the same in all (regular exercise) and the overall angle remains the same (benefits). But the angle narrows and shifts slightly from topic sentence to topic sentence as the writer brings in different supporting ideas and research.

Notice that in the examples above, the topic sentence reflects back to the overall thesis (A regular exercise regime creates multiple benefits, both physical and emotional.) and introduces the reader to the specific topic and angle of each paragraph (improving sleep, reducing stress, etc.).

Sometimes, you may need multiple paragraphs to help work your way behind the ideas related to one topic sentence because you have a lot of supporting information. An effective topic sentence not only introduces the topic of each paragraph, but it reminds the reader of the overall thesis, driving home the point of the piece of writing.

Effective annotating includes taking careful notes to extract the main ideas from a reading. In order to find the main ideas, you’ll need to know how to identify the thesis statement and topic sentences in each paragraph. This video will walk you through that process, and also highlight some other key components of essays, like supporting details and transitional words and phrases.

You can view the transcript for “Annotating an Essay or Book” here (opens in new window) .

In our next section, we’ll move beyond the topic or key sentence to all the other pieces that make up a strong paragraph, like supporting details and transitional words and phrases.


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