Topic Sentences

Learning Objectives:

  • Identify the topic sentence in a paragraph.
  • Develop an effective topic sentence.

The topic sentenceA sentence that contains the controlling idea for an entire paragraph and is typically the first sentence of the paragraph. is the main pointThe most important idea in a paragraph. Main points support the main idea of a reading., or controlling ideaThe specific idea that controls a paragraph, including the purpose, subject, and the writer's point of view., of a paragraphA selection of a writing that is made up of sentences formed around one main point. Paragraphs are set apart by a new line and sometimes indentation.. In this lesson, you will learn how to identify an authorA person who wrote a text.'s topic sentence and how to write your own.

Identify the topic sentence
If you cannot identify the topic sentence of a paragraph, your comprehensionThe ability to understand a subject, reading, or idea. will suffer since you will not be able to understand the author's main ideaThe most important or central thought of a reading selection. It also includes what the author wants the reader to understand about the topic he or she has chosen to write about.. The following four steps will help you identify the topic sentence.

Step 1. Find the topic of the paragraph.
Do not confuse the topicThe subject of a reading. with the topic sentence. The topic is simply the who or what being discussed in the paragraph, while the topic sentence includes the topic and the point being made about it. Knowing the topic will point you towards the topic sentence. Circle the words used most often in the paragraph. Also circle any synonymsA word or phrase that has an identical or very similar meaning to another word. Example: tiny is a synonym for small. or pronounA part of speech that substitutes for a noun or noun phrase. Examples include: I, he, you, they. references.

Step 2. Identify the keywords that signal a topic sentence.
While not all topic sentences include keywordsWords that are important to understanding the meaning of a passage or reading., when you come across sentences with any of these phrasesA set of words that express an idea. A phrase may or may not form a complete sentence., you can be fairly certain that it is the topic sentence.

Topic Sentence Keywords


A number of steps


Several kinds of

The disadvantages of


A couple of effects


A number of similarities

Some differences


A series of


A number of factors

A number of benefits

Step 3. Identify the major details.
Sometimes, the supporting detailsStatements within a reading that tie directly to major details that support the main idea. These can be provided in examples, statistics, anecdotes, definitions, descriptions, or comparisons within the work. are easier to find than the topic sentence. If so, identify all major detailsThe larger points within a reading that support the main idea., and see what they have in common. This is an especially effective technique for paragraphs that do not have an explicitly stated topic sentence. 

Step 4: Look beyond the first sentence to identify the topic sentence.
Do not assume that the topic sentence is the first sentenceA group of words, phrases, or clauses that expresses a complete thought. A complete sentence has these characteristics: a capitalized first word, a subject and a predicate, and end punctuation, such as a period (.), question mark (?), or exclamation mark (!). of the paragraph. In most paragraphs, the topic sentence is one of the first sentences; however, that is not always the case. Sometimes, the writer includes some introductory material before getting to the point or the writer sums up the major details with a topic sentence at the end.

For example, look at the following paragraph:

Most environmental scientists agree that human activity directly contributes to global warming. Luckily, most also agree that human activity also has the potential to reverse global warming. There are several changes that average Americans can make to lower their carbon footprints. The first change they can make is to reduce, reuse, and recycle as often as possible. A large amount of pollution is expelled in the production of new products; whereas, it requires no additional fossil fuels to reuse an item. Recycling, while still using fossil fuels to reprocess the product, consumes much less energy than creating a new item from scratch. Using public transportation is another way that Americans can reduce their carbon footprints. Cars are the single biggest contributor to greenhouse gases. Walking to work and school is even more beneficial. Lastly, more Americans can adopt alternative energy sources. Installing wind turbines and solar panels reduces our reliance on fossil fuels, which will reduce the harmful emissions they cause. By adopting all three of these changes, Americans can help ensure a brighter future for generations to come.

Even though the first sentence has a solid main idea that could be the topic of a paragraph, namely that humans cause global warming, the rest of the paragraph is not about that topic. Following the steps outlined above helps identify the topic sentence.

Step 1. Find the topic of the paragraph.
The topics are Americans, global warming, and change.

Step 2: Identify the keywords that signal a topic sentence.
"There are a several changes"

Step 3: Identify the major details.

What do all of these major details point to? Americans can make specific changes to help global warming.

Step 4: Look beyond the first sentence to identify the topic sentence.
In this case, the topic sentence is the third sentence. "There are a several changes that average Americans can make to lower their carbon footprints."

Develop a topic sentence
Use these guidelines to help you develop effective topic sentences of your own.

  1. Know what you want to write and the point you want to make about it.
  2. When appropriate, incorporate the above keywords into your topic sentence to signal its location to your reader.
  3. Develop major details to support your topic sentence and vice versa.
  4. Place the topic sentence early in the paragraph. This is not mandatory, but it is a strategy that will ensure that you consciously have a topic sentence in your paragraph to guide you as you write.

For example, if you had an assignment to develop a topic sentence for a process paragraph where you need to outline the steps in the rock cycle, the topic sentence might look something like this:

There are three steps in the rock cycle—igneous, sedimentary, and metamorphic.