The thesis statement often appears at the end of the introductory paragraph, but it can also appear at the beginning of the introductory paragraph. Much work-related writing, in which a straightforward approach is most effective, commonly begins with the thesis.
Thesis at beginning of introduction
Thesis at end of introduction
If you are writing an argument paper, you need an explicit thesis statement. But for some other types of writing, it may be difficult or impossible to express the central idea in a thesis statement; or it may be unwise or unnecessary to put a thesis statement in the essay itself.
If you are writing a literature review or a reflective essay or a lab report, you might not have a thesis statement. But you still need to indicate your purpose for writing and give readers an idea of what to expect; there are many ways to do so.
A personal narrative, for example, may have a focus too subtle to be distilled in a single sentence, and such a sentence might ruin the story. Strictly informative writing, like that found in many business memos, may make the purpose clear in the subject line. In such instances, do not try to force the central idea into a thesis sentence. Instead, think in terms of an overriding purpose, which may or may not be stated directly.
It might be helpful to examine model papers from various disciplines to see how student writers construct introductions that establish the central purpose of the paper, whether with a direct thesis statement, an indirect thesis, or a statement of purpose and scope.
Academic English: Using a direct approach
Effective thesis statements