The Topic Sentence. Think of it as the thesis statement of a paragraph. Once you understand the function of a thesis statement in your paper, topic sentences make much more sense. You might want to review Lesson One on thesis statements before tackling this lesson on topic sentences.

Topic sentences establish the main idea of the paragraph they lead off. Topic sentences are generally found at the beginning of a paragraph, especially when it comes to the papers you will write in your freshmen composition courses. They set up the discussion of the paragraph and introduce the paragraph’s primary point or argument.

Like a thesis statement, a good topic sentence should be specific and concrete. It should clearly introduce the paragraph and get right to the point. Don’t open a new paragraph with a fluffy, meaningless statement that fails to introduce the paragraph’s main idea. In an argumentative essay, it should be relatively clear to the reader what each paragraph is about simply from the context of the sentence that begins it.

Examples of Topic Sentences

Let’s get meta here for a second and examine the previous two paragraphs. Notice the opening line of paragraph two.

Topic sentences establish the main idea of the paragraph they lead off.

See how this topic sentence clearly introduces the argument I’m making in this paragraph?  Each sentence following this opening line relates to the idea established here. Look also at the topic sentence of paragraph three:

Like a thesis statement, a good topic sentence should be specific and concrete.

This sentence tells us as readers the paragraph will make the point that a topic sentence should be specific and concrete. Notice how all other sentences in the paragraph discuss that point and only that point.

If you find your paragraph begins to wander into territory other than that which is elucidated in the opening sentence, it’s a good sign that one of two things is happening. Either, 1) You have a weak topic sentence and, therefore, aren’t sure what should be covered in the paragraph, or 2) It’s time for a paragraph break and a new topic sentence.

Topic Sentences as Transitions

Effective use of paragraph transitions is a crucial skill that helps set good writers apart. We will cover proper transition implementation extensively in the next lesson, but let’s briefly point out here how topic sentences can incorporate transitional phrases that facilitate smooth connections between paragraphs in your essays.

These smooth connections help the reader follow the logic of your argument, and good topic sentences incorporate these connections so subtly you might not even notice it happening. Not only do they set up the new paragraph, but they also often echo a key phrase of the previous paragraph.

Did you see what I did there? Stop and re-read the previous topic sentence. Take note of the transitional phrase it begins with: “these smooth connections.” See how that phrase echoes a key phrase of the paragraph before it? It shows the reader we’re still discussing smooth connections, but that we are slightly shifting the point to a new (but related) main idea.

Strong topic sentences set up the new paragraph but also show how the new paragraph is related to the ongoing discussion.

Further Study on Topic Sentences

It should be noted that not every paragraph is going to have an obvious, structured main topic sentence. As your writing skills grow, you will find this formulaic structure of opening paragraphs with topic sentences can occasionally be a bit limiting. Watch how your favorite non-fiction writers handle topic sentences. You’ll see they often employ this strategy of introducing the paragraph’s main idea, but sometimes they deviate from the structure for stylistic reasons.

As you grow more comfortable with your own voice and writing style, you too can occasional explore other paragraph structures, but you will find that sticking to this formula of beginning paragraphs with carefully crafted topic sentences will serve you well in Developmental Writing, as well as in your English 101 and English 102 classes.

When you’re ready, move on to Lesson Three: Transitions, or check out our Resources List for Developmental Writing Students and Teachers.