This question comes up more than you'd expect. I've seen it in college papers, blog drafts, and even submissions to publishers. The confusion makes sense because the rule changed, and not everyone got the memo.
Here's the full breakdown of when to italicize, when underlining is still acceptable, and how to handle the edge cases.
The Short Answer: Italicize, Don't Underline
In any typed or digital document, italicize book titles. "I just finished reading *The Great Gatsby*." Not underlined. Not in quotation marks. Italicized.
This applies across all major style guides: APA (7th edition), MLA (9th edition), Chicago Manual of Style (17th edition), and AP Style. The consensus is complete. If you're typing on a computer, phone, or tablet, italicize book titles.
When Underlining is Still Acceptable
The only situation where underlining a book title is correct is in handwriting. If you're writing by hand, on paper, or on a whiteboard, you can't produce italics. Underlining is the handwritten substitute for italics. This is the original purpose of the underlying convention.
In the typewriter era, most machines couldn't produce italic text. Writers underlined titles in manuscripts, and typesetters converted those underlines to italics during the printing process. Now that every word processor, email client, and text editor supports italics, the underline workaround is no longer needed for typed text.
Some teachers still accept underlining in student papers. If your instructor requires it, follow their guidelines. However, in professional writing, publishing, and journalism, italics are the standard.
What About Quotation Marks?
Quotation marks are for shorter works. Book titles get italics. Chapter titles get quotation marks. The same logic applies across all media:
Italicize (the larger work): book titles, album titles, movie titles, TV show titles, magazine names, newspaper names
Quotation marks (the smaller work): chapter titles, short story titles, article titles, song titles, individual episode titles, poem titles
So: *The Great Gatsby* is italicized because it's a full book. "Chapter 1" or a short story like "The Tell-Tale Heart" goes in quotation marks because it's a component of a larger work.
Style Guide Comparison
APA Style (7th Edition)
Italicize book titles in text and in the reference list. The first letter of major words is capitalized (title case). Example: *The Elements of Style*.
MLA Style (9th Edition)
Italicize book titles in text and on the Works Cited page. Title case capitalization. Example: *To Kill a Mockingbird*.
Chicago Manual of Style (17th Edition)
Italicize book titles in text, footnotes, and bibliography entries. Chicago provides the most detailed guidance on edge cases, including sacred texts (not italicized) and book series titles (not italicized).
AP Style
AP puts book titles in quotation marks rather than italics. This is the exception among major style guides and applies primarily to journalism. If you're writing for a newspaper or news website, follow AP. For everything else, italicize.
Special Cases
Sacred texts
The Bible, the Quran, the Torah, and other sacred texts are not italicized, underlined, or placed in quotation marks. They're treated as proper nouns.
Book series titles
Individual books in a series are italicized: *Harry Potter and the Sorcerer's Stone*. The series name itself is not italicized: the Harry Potter series. The same applies to other series, such as The Kingkiller Chronicle or A Song of Ice and Fire.
Titles within titles
If a book title contains another title, the contained title is set in regular (non-italic) type. Example: *Understanding* To Kill a Mockingbird. This is one of the few cases where the formatting gets complicated.
Final Thoughts
Getting the details right in your writing matters whether you're formatting an academic paper or writing a book for the first time. Consistent formatting signals professionalism.
Related Resources
FAQ
Here, I will answer the most frequently asked questions about underlining book titles.
Do I underline book titles in an essay?
No. Italicize them. All major academic style guides call for italics in typed documents.
What about book titles in emails or text messages?
Italicize if your platform supports it. If it doesn't (as in plain-text emails or SMS), use all caps or quotation marks as a workaround. Most email clients and messaging apps now support basic formatting.
Should book titles be bold?
No. Bold is not a standard formatting treatment for titles in any style guide. Use italics.
How do I format a book title in a bibliography?
Italicize the title. The specific formatting (capitalization, punctuation, placement) depends on your style guide. APA, MLA, and Chicago each have somewhat different bibliography formats, but all three italicize the title.