Topic Sentences

What is a Topic Sentence?

To explain what a topic sentence is, we first have to outline the two basic principles of paragraphing. First, each paragraph in a text should address one topic or aspect (and not several at the same time). Second, each paragraph should have a specific purpose and add something new to the text.

A topic sentence is a sentence which captures the specific purpose of the paragraph – the most central issue, the very essence of the paragraph. The topic sentence is often the first sentence of the paragraph, signaling what the paragraph is about.

The topic sentence must be fairly general – you cannot fit everything that you want to write about a topic into one single sentence. In the rest of the paragraph, you develop and support the issue signaled in the topic sentence, and potentially give relevant examples.

Topic Sentences Are Good for Your Reader

Topic sentences help your reader navigate the text, as she knows from the very beginning of the paragraph what the paragraph will be about. A skilled reader of scientific texts often expects a topic sentence – consciously or unconsciously – and may therefore be vaguely confused if there is none, or initially believe that your paragraph is about something else.

Topic Sentences Are Good for You as a Writer

Topic sentences make a text reader friendly, but they are equally good for you as a writer, and may be powerful tools for working on your text. Working with topic sentences forces you to consider the relevance of each of your paragraphs – what is your main point in this particular paragraph? What is the most central issue? What needs to be foregrounded?

Topic sentences can also help you revise your text to make it more coherent and concise. Once you have formulated a topic sentence, you can go through each sentence of the paragraph and make sure that it relates to the topic sentence. It should, as the paragraph should only deal with one topic or aspect. But quite often, you will discover sentences that do not clearly relate to the topic sentence. You then have two choices: you can either formulate a new topic sentence which better captures the essence of the entire paragraph, or take away any sentence that does not fit. The sentence may fit better in another paragraph, it may need to be developed into a separate paragraph to address the issue in depth – or it may not be entirely relevant (and should then be removed).