Headings and subheadings in the body of your research project can help organize and structure your writing, but you should avoid overusing them. Headings should never be used to compensate for poor structure or to explain an underdeveloped idea, and they are generally not needed in short, essay-length works. When headings are called for in your writing project, keep them short and observe the basic guidelines below.

Consistency in the styling of headings and subheadings is key to signaling to readers the structure of a research project. Word processing software often has built-in heading styles. Headings in the body of your research project should be styled in descending order of prominence. After the first level, the other headings are subheadings—that is, they are subordinate. Font styling and size are used to signal prominence. Each level 1 heading should appear in the same style and size, as should each level 2 heading, and so on. In general, a boldface, larger font indicates prominence; a smaller font, italics, or lack of bold can be used to signal subordination. For readability, avoid using all capital letters for headings (in some cases, small capitals may be acceptable).

No internal heading level should have only one instance. For example, if you use a level 1 heading, you should have at least one other level 1 heading. (The exceptions are the paper or chapter title and the headings for notes and the list of works cited.)

In the body of the paper, headings should be flush with the left margin, not indented or centered. For readability, include a line space above and below a heading.

Generally avoid using numbers and letters to designate headings unless you are working in a discipline where using them is conventional.

Capitalize and punctuate headings like the titles of works as explained in 2.90–2.119.

When possible, make headings and subheadings parallel in structure—that is, ensure that headings at the same heading level match one another grammatically and share other basic similarities. When headings are parallel, readers can more easily grasp the structure and content of a research project as a whole.

First, check that headings are of the same grammatical category. In the list, consider revising the heading “Can Online Sources Be Plagiarized?” so that it is parallel with the other headings. Check also for number agreement. If headings use a mix of singular and plural nouns, try to adjust them so that they are all singular or all plural.

If you have a mix of headings with and without subtitles, consider editing them so that all headings at the same level either contain a subtitle or do not. In the following list, you could omit the subtitle from “Learning about Online Research: Broad and Narrow Searches” to make the headings parallel.

Check your headings for consistent length—you may quickly identify any outliers. Below, the first heading is much longer than the others, so you might forgo the quotation, shorten the subtitle, or both.