There has historically been some debate over whether book titles should be underlined, italicized, or put in quotation marks when writing an essay. Different style guides have recommended different approaches, which has led to some confusion. The general consensus today among most style manuals is that book titles should be italicized rather than underlined when referencing them in essay writing and other academic works.
When typewriters were commonly used, underlining was a preferred way to emphasize book titles since there was no straightforward way to italicize on a typewriter. Underlining served as a visual substitute to set off and highlight book titles. With the advent of word processors and desktop publishing software, italicizing text became much easier to do. As a result, most modern style guides now recommend italicizing book titles instead of underlining them.
Some key style guides that recommend italicizing rather than underlining book titles include:
The Modern Language Association (MLA) style guide, which is often used for papers in the humanities. MLA clearly states that book titles should be italicized, not underlined or put in quotation marks.
The Chicago Manual of Style, followed by many in the social sciences, also specifies that book titles should be italicized and not underlined in running text.
The Associated Press (AP) Stylebook, used widely in journalism, also dictates that book titles should be italicized, not underlined when referenced in essays and articles.
The American Psychological Association (APA) style guide used in psychology and other sciences also says that book titles should be italicized rather than underlined or in quotation marks.
The standard practice today accepted by nearly all major style guides is to italicize book titles, rather than underline them, when including them in an essay or research paper. Italicizing book titles sets them off visually in a clear, standardized way that signifies to readers that this text refers to a independently published creative work.
There are a few instances where underlining a book title might still be acceptable according to some guides:
If for some reason italicization is not possible (such as when writing by hand), then underlining can be used as a substitute. This would be a rare case in modern word processed writing.
In non-academic, informal writing contexts where there is no strict adherence to a style guide, an author could optionally underline a book title for emphasis. But in research papers, it’s best to italicize to conform to standardized academic practices.
Some older style guides, textbooks, or manuals published prior to widespread computer usage may still recommend underlining book titles out of tradition. But for contemporary writing, italicizing is preferred.
When writing an academic essay, research paper, or other formal written work, you should italicize any book titles referenced in the text, rather than underline them. Italicizing has become the standard formatting convention accepted by all major modern style guides. It clearly sets off book titles visually in a standardized way for readers. Underlining book titles in written work could potentially mark you as not fully adhering to academic formatting best practices. While underlining may still be acceptable in rare cases, italicizing is clearly the safer, most widely accepted approach. Sticking to italicizing book titles in your papers will help ensure your writing meets institutional formatting guidelines.
The same rule generally applies when citing book titles in a bibliography or reference list at the end of an essay as well. Most style guides consider it unnecessary to italicize or underline titles that are already distinguished from normal text in a bibliography or reference entry. It is still acceptable to do so per some guides if desired. The key in the main body of an essay is always to italicize book titles rather than underline them for the reasons mentioned above. When writing an academic essay, always format any referenced book titles using italics rather than underlining to conform to standardized style guide practices.
Now, there are a few additional noteworthy details in certain style guides regarding capitalization of book titles:
MLA recommends italicizing the main words of a book title (but not articles like “a”, “an”, or “the”) and capitalizing these words. For example: To Kill a Mockingbird.
Chicago and APA style dictate using title case capitalization for book titles, meaning capitalizing major words except articles, prepositions, and conjunctions. So the aforementioned book would be: To Kill a Mockingbird.
In Chicago style, very long book titles that are “noisy” with many capitals may optionally be sentence-style capitalized like normal prose for readability.
For book titles in bibliographies, MLA says to maintain the capitalization used in the actual published title. Chicago and APA recommend following normal capitalization and typographical style of the original title.
When citing book titles within essay text, use italics and follow capitalization preferences of your chosen style guide (MLA, Chicago, APA, etc.). But always format using italics rather than underlining for visual separation as per modern standardized academic practices. Carefully adhering to widely accepted style guides for small things like capitalization and formatting of bibliographic elements helps ensure your writing meets or exceeds formatting expectations. Following guidelines consistently creates a clean, professional presentation.
There is one final edge case to discuss regarding whether to italicize book titles – self-published e-books. For e-books distributed solely as PDF or e-book reader files with no true “publishing” per se, the rules are somewhat less defined since they don’t technically fit the standard definition of a “published” book with an ISBN, publisher, etc. For these works, some guides recommend either:
Italicizing the title just as with traditionally published works
Putting the title in double quotation marks instead of italics
Not emphasizing the title formatting at all (leaving it in regular roman text)
Most experts agree the safest approach for an academic essay is to still italicize e-book titles for consistency, even if they weren’t “formally published.” This maintains a clean visual separation of title text that is easily recognized by readers. Only putting in quotation marks or skipping emphasis could risk the title blending into the surrounding prose too much.
The clear standard when writing an essay is to always format referenced book titles using italics rather than underlining. Italicizing book titles is the approach widely accepted by all major style guides. Underlining is rarely if ever appropriate in modern academic writing. Be sure to also follow any rules in your specific style guide around book title capitalization. Carefully observing guidelines for small stylistic elements like this helps ensure your writing stylizes references properly and maintains a high level of professionalism. Whether a traditionally published book or self-published e-book, italicizing titles is the best practice to adopt.
Andrew Stroud