Writing: Main Idea, Thesis Statement, and Topic Sentences

Amanda Palmer, Doresa Jennings
  • Author
    Amanda Palmer

    Amanda Renaud has taught Middle School and High School English for 4 years. She has a Master's of Education in Curriculum and Development with a minor in Reading Intervention from Concordia University. She is certified to teach English and Humanities in Washington and Texas.

  • Instructor
    Doresa Jennings

    Doresa holds a Ph.D. in Communication Studies.

Learn how to write the main idea of an essay, the thesis statement, and the topic sentence. Study examples of each and compare their meanings in essay writing. Updated: 01/12/2022

Table of Contents


Main Idea, Thesis Statement & Topic Sentence

It is important for a written piece - an essay, for example - to have structure and organization. Structure and organization help a writer clearly communicate ideas and help the reader understand the ideas being communicated. The main idea, thesis statement, and topic sentences all provide structure to an essay. It is important for both readers and writers to understand the roles of each of these in order to maintain clear communication and understanding of ideas.

  • Main idea: The concept that is being discussed or analyzed throughout the entire essay.
  • Thesis statement: A one-to-two sentence statement that is usually found in the introduction of the essay and explains the main argument of the entire piece. The body paragraphs and conclusion will all connect to and support this statement.
  • Topic sentence: A key sentence at the paragraph level that discusses and elaborates on specific points from the thesis statement.

The main idea, thesis statements, and topic sentences structure an essay.

Main Idea_Essay Structure

Difference Between Thesis Statement and Topic Sentence

It is important to be able to differentiate between a thesis statement and a topic sentence. Although they have similar purposes, they have different roles in communicating the ideas of the piece; one gives the main idea for the entire essay and the other the main idea in supporting paragraphs.

The thesis statement summarizes the argument or analysis that will be discussed throughout the entire essay. It is usually one sentence long, and it is usually located in the introduction paragraph. The supporting paragraphs that follow the introduction explain the important points and ideas of the thesis.

A topic sentence is the key sentence in a supporting paragraph that explains particular points of the thesis of the entire work. A topic sentence tells what that particular paragraph is about; it connects the supporting ideas in it to the argument or analysis that is explained in the thesis statement. Topic sentences occur throughout the essay near the beginning of each paragraph and help transition to new supporting ideas.

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Main Idea of an Essay

The main idea is the concept being expressed or examined throughout the essay. The main idea is the gist, meaning what it is mostly about; it is what the whole text says about the topic of the essay. The thesis statement, topic sentences, and supporting sentences will all connect to this idea.

How to Write a Main Idea

An effective main idea can be supported by the details, analysis, and arguments found in the essay. To write a main idea statement, consider the general topic and what will specifically be shared about that topic. The main idea narrows the topic from a large general idea to a more specific idea. Then the main idea statement will be written as a statement that explains what will be shared about that idea.

1. Select a general topic: coffee

2. Narrow down the topic to a specific idea: organic coffee options

3. Write a statement that explains what will be shared about this idea: There are many benefits to choosing organic coffee.

The main idea statement explains the concept that will be discussed throughout the essay.

Main Idea_How to write a main idea

Thesis Statement

A thesis statement, sometimes referred to as the central idea statement, clearly explains the argument or analysis of the main idea. It is important because it helps readers understand what the essay is about. It is one to two sentences, usually located in the introduction paragraph, and explains the argument or analysis that will be discussed throughout the remainder of the essay. The thesis statement will help readers understand the purpose of the essay.

Writing a Thesis Statement

A thesis statement or central idea statement will indirectly state the purpose of the essay. After determining the main idea statement, writers should create a purpose statement. A purpose statement identifies the audience and explains how and why the content will be presented to the audience.

The purpose statement for the organic coffee example could be the following:

To convince readers to drink organic coffee instead of conventional coffee.

The purpose statement will not be included in the essay, but it helps the writer identify in their mind the reason for writing the essay and the argument being presented. The thesis statement can then be created using the purpose statement as a guide. The thesis statement will explain the main argument or analysis of the essay. The thesis statement should include the reasons that will be presented in the essay as well as the counterargument, if there is one.

Using this same organic coffee example, the following thesis statement can be crafted:

Although it may be easier and cheaper to buy conventional coffees, there are many benefits to drinking organic coffee, including health benefits, environmental benefits, and economic benefits.

How Many Sentences Should a Thesis Statement Be?

The thesis statement can be one to two sentences in length. It is critical that the argument or analysis is presented clearly, so clarity is the priority when constructing a thesis statement.

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Frequently Asked Questions

How do you write a main idea in an essay?

To write the main idea of an essay, a writer has to decide on a topic and what they would like to share with the audience about that topic. The topic needs to be narrowed down into a specific idea that can be explained and described throughout the essay.

What is a thesis or central idea statement?

A thesis statement is one sentence usually found in the introduction of the essay that explains the main argument or analysis of the essay. It will include the main points the author is trying to make as well as an overview of the supporting details that will be used to defend the argument.

How many sentences can your thesis be?

A thesis statement is one to two sentences; clarity for complex arguments is key rather than the number of sentences.

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