How to Write a College Expository Essay

An expository essay explains a concept, investigates an idea, or presents evidence for an opinion. According to Purdue's Online Writing Lab, in-class writing assignments and exams frequently instruct students to use an expository essay format. Expository essays can be developed using several different organizational patterns, depending upon the assignment, writing prompt or topic.


No matter which organizational pattern you select for an expository essay, the essay must include an introduction that concludes with a clear, defined thesis sentence. Following the thesis sentence, body paragraphs should cover the main points included in the thesis. Each body paragraph should have a topic sentence. Students should use factual, logical, statistical or anecdotal information in each body paragraph. A good conclusion reflects the body paragraphs and the thesis statement but does not repeat the thesis.

Compare and Contrast

A writing assignment to compare two approaches to a problem, two people, or two different products is suitable for a comparison and contrast expository essay. For example, if you are assigned to compare Civil War generals Grant and Lee, identify the main points of comparison between the two. Include these points of comparison in the thesis statement. Organize body paragraphs by covering each point of comparison, both similarities and differences, between the generals. Alternatively, write body paragraphs about Grant, then transition to paragraphs about Lee before writing a conclusion that reflects the thesis.

Cause and Effect

Assignments that request students to cover the causes of a disease, a business success or failure or an historic event invite a cause and effect expository essay. If you are asked to write about the causes of heart disease, identify the primary causes and include them in the introduction and thesis statement. Organize body paragraphs by each cause, such as smoking, diet and lack of exercise. Conclude reflecting the causes you have covered.

Paragraph Structure

Structure within paragraphs is important. Be certain each paragraph covers one subtopic and has a clear topic sentence. Include specific supporting evidence for the topic sentence. For example, if you are writing a paper in business class about the causes and effects of the 2001 Enron scandal, one paragraph could cover the woman who uncovered the scandal, Sherron Watkins. The paragraph should include facts and quoted information about Watkins' role as whistleblower.