How to Write a Thesis Statement

Your thesis states the argument you will make or defend in your essay. In other words, your thesis presents a claim that you will support with evidence. The entire essay will then relate back to that claim.


  1. A thesis must be arguable—a claim you can support with evidence; it cannot simply be a statement of fact. Facts are true statements and, as such, do not need to be defended.

    Fact: Dinosaurs went extinct millions of years ago.

    Thesis: Because of the large amount of geological and paleontological evidence suggesting as much, it is probable that the impact of a giant meteor striking the earth caused the extinction of the dinosaurs.

  2. A thesis should be narrow enough for you to be able to discuss your argument in depth in the number of pages you have, but not so narrow that you have nothing to say. Assuming you are writing a 7-10 page essay, consider each of the following:

    Too Broad: Dinosaurs are awesome. (There are too many variables to cover in 7 pages. There is no reason given for taking this position, and it is not clear how the author intends to define “awesome”).

    Too Narrow: The Tyrannosaurus Rex is the most popular and well-known dinosaur because it has been featured in more movies and television shows than any other dinosaur. (After listing appearances of the Tyrannosaurus Rex in movies and television, there is little else to say to defend this position).

  3. A thesis should give direction to your paper and let your reader know what to expect. This sample thesis below gives an arguable possibility of the reason behind dinosaur extinction.

    Just Right: Dinosaurs reached extinction because they were unable to adapt to changes occurring in their environment.

  1. Find your topic. Example: Dinosaurs.
  2. If necessary, narrow your topic by asking questions such as who, what, when, or where.

Example: When did dinosaurs disappear? What caused dinosaurs to become extinct? Who were the dinosaurs’ predators?

  3. Give your opinion about your topic, including a why or how or who cares element.

    Example: Due to advances in cloning technology, scientists could potentially bring dinosaurs back from extinction.

  4. You may need to do some exploratory writing before you know what your thesis is, so start with a preliminary, tentative thesis. Adjust your thesis throughout the writing process to match the argument you ultimately make.

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