Book Title Capitalization: Rules for Every Major Style Guide

Whether you're writing a bibliography, referencing a novel in an essay, or designing a book cover, you need to capitalize the title correctly. But "correctly" depends on which style guide you're following - and each one handles book titles a little differently.

This guide covers book title capitalization rules for AP, APA, MLA, and Chicago style. You'll learn how to handle subtitles, series names, titles within titles, and the tricky edge cases that come up with real book titles.

The Basics: How Book Titles Work

Book titles almost always use title case - that means you capitalize the first word, last word, and all major words. Articles (a, an, the), short prepositions (of, in, on, at, to, for, by), and coordinating conjunctions (and, but, or, nor, yet, so) stay lowercase unless they start or end the title.

This applies whether you're writing the title on a cover, in a sentence, or in a citation. The one big exception is APA reference lists, where book titles switch to sentence case. We'll cover that in detail below.

The differences between style guides come down to specific word-length rules, how they handle hyphenated words, and what counts as a "major" word. These details matter when your book title contains words like "between," "through," or "is." If you want a side-by-side comparison of all four major style guides, check out our title case styles comparison.

Book Title Rules by Style Guide

Each style guide agrees on the big picture - capitalize major words, lowercase minor ones. But they disagree on the details. Here's what each one says about capitalizing book titles specifically.

AP Style

AP style capitalizes words of four or more letters. That means prepositions like "with," "from," "over," and "between" get capitalized, while "of," "in," "on," "at," "to," "for," and "by" stay lowercase. AP is the standard for journalism, so you'll follow these rules when referencing book titles in news articles, reviews, and blog posts.

• Capitalize words with 4+ letters, including prepositions and conjunctions
• Lowercase articles (a, an, the) unless first/last word
• Lowercase prepositions with 3 or fewer letters: of, in, on, at, to, for, by
• Lowercase coordinating conjunctions with 3 or fewer letters: and, but, or, nor
• Always capitalize "yet" and "so" (they have 3 letters but AP treats them as significant)

APA Style (7th Edition)

APA uses the same four-letter threshold as AP for title case. The official APA Style site explains the critical distinction: APA uses title case for book titles in your text and sentence case for book titles in your reference list. This dual system trips up students constantly.

• In text: Title case - capitalize words of 4+ letters, plus all major words
• In references: Sentence case - capitalize only the first word, first word after a colon, and proper nouns
• Capitalize both parts of hyphenated major words (e.g., "Self-Report")

MLA Style (9th Edition)

MLA doesn't use a word-length rule. Instead, it capitalizes based on part of speech. All nouns, verbs, adjectives, adverbs, and subordinating conjunctions get capitalized regardless of length. Only articles, prepositions, coordinating conjunctions, and "to" in infinitives stay lowercase.

• Capitalize all major words regardless of length
• "Is," "be," "am," "are," "was" are always capitalized (they're verbs)
• Capitalize subordinating conjunctions: "because," "although," "if," "when"
• Lowercase only articles, prepositions, coordinating conjunctions, and "to" in infinitives
• Uses title case in both text and Works Cited

Chicago Manual of Style (17th Edition)

Chicago style lowercases prepositions regardless of length (unless they're used as adverbs or adjectives). The Chicago Manual of Style is the standard in book publishing. So "between," "through," and "against" stay lowercase in Chicago - unlike AP and APA, where they'd be capitalized because they have 4+ letters.

• Lowercase prepositions of any length (including "between," "through," "against")
• Capitalize prepositions when used as adverbs or adjectives ("Turn On the Light")
• Lowercase articles and coordinating conjunctions
• Always capitalize the first and last word
• Uses title case in most contexts, sentence case in some bibliography formats

How to Capitalize Subtitles

Many books have subtitles separated by a colon. The rule is consistent across all four major style guides: always capitalize the first word after the colon, even if it would normally be lowercase.

This applies whether the subtitle follows a colon, an em dash, or (less commonly) a period. The word after the break gets treated as the start of a new title.

Some real book titles that demonstrate this rule:

• Sapiens: A Brief History of Humankind - "A" is capitalized because it follows the colon
• Educated: A Memoir - same rule, even though the subtitle is just two words
• The Sixth Extinction: An Unnatural History - "An" follows the colon, so it's capitalized
• Quiet: The Power of Introverts in a World That Can't Stop Talking - "The" follows the colon

Series Names, Editions, and Volumes

Book series names follow the same title case rules as individual book titles. When you reference both the series and a specific volume, you capitalize both according to your style guide.

• Harry Potter and the Order of the Phoenix - "the" and "of" are lowercase because they're articles/prepositions mid-title
• A Song of Ice and Fire - "of" and "and" lowercase, "Ice" and "Fire" capitalized as nouns
• The Lord of the Rings: The Return of the King - "of" and "the" lowercase in the middle, but "The" capitalized after the colon

For editions and volumes, the conventions vary slightly:

Special Cases: Titles Within Titles and More

Some book titles contain other book titles, song names, or quoted phrases. These get complicated, but the rules are manageable once you know them.

Titles Within Titles

When a book title contains the name of another work, you keep the inner title's formatting but adjust it to distinguish it from the outer title:

• Book title within a book title: remove italics from the inner title. Example: Reading Lolita in Tehran
• Short work within a book title: keep the quotes. Example: The Philosophy of "As If"
• Both still follow standard title case rules for capitalization

Names and Foreign Words

Proper nouns within titles always stay capitalized, regardless of their position. Foreign words that have been adopted into English (like "et cetera" or "versus") follow the same rules as English words. Untranslated foreign titles follow the capitalization conventions of the original language.

Numbers and Symbols in Titles

Numbers in titles don't affect capitalization rules. Treat the word before and after a number the same as you would anywhere else. For titles that start with a number, the second word follows normal rules - it's only capitalized if it's a major word. Example: 1984 (just the number), 20,000 Leagues under the Sea (Chicago: "under" lowercase as a preposition).

Italics, Quotes, and Formatting

Capitalization is only half the equation - you also need to know whether to italicize the title or put it in quotation marks. The general rule across all style guides:

AP style is the exception - it doesn't use italics in print. Instead, AP puts book titles in quotation marks: "The Great Gatsby." But in online contexts, most AP-style publications have adopted italics for clarity.

20 Book Title Examples: Wrong vs Right

These examples show the most common capitalization mistakes people make with real book titles. The corrections follow standard title case rules that apply across most style guides. For style-specific differences, check the rules section above.

Notice the pattern: most mistakes involve capitalizing short prepositions (of, in, with) and articles (the, a) that should stay lowercase in the middle of a title. The style-guide differences only show up with 4+ letter prepositions like "with" and "over." For more common mistakes like these, see our 15 most common title case mistakes guide.

Book Titles in Reference Lists and Bibliographies

This is where the style guides diverge most dramatically. The capitalization rules change depending on whether you're mentioning a book in your text or listing it in your references at the end.

The APA sentence case rule catches people off guard every time. When you write about The Great Gatsby in a paragraph, you use title case. But in your APA reference list, that same book becomes: Fitzgerald, F. S. (1925). The great Gatsby. Scribner. Only "The" is capitalized because it's the first word, and "Gatsby" because it's a proper noun.

For a deeper comparison of sentence case and title case rules, read our sentence case vs title case guide. And for academic-specific formatting, see academic paper title capitalization.

Book Covers and Marketing Materials

Book covers, Amazon listings, and publisher catalogs don't follow any one style guide. Designers and publishers make their own capitalization choices for visual impact, and that's perfectly fine. You'll see all-caps titles (where the crawdads sing), stylized lowercase (the goldfinch), and everything between.

But when you write about those books in text - in a review, a school paper, a blog post, or a social media caption - you should use standard title case regardless of how the cover looks. The cover design is a visual choice; your capitalization is a grammar choice.

Self-published authors often ask about capitalization for their own book covers. The short answer: you have creative freedom on the cover, but use title case in your metadata (Amazon title field, ISBN registration, copyright page, press materials). Search engines and library catalogs expect title case, and inconsistent capitalization in metadata can cause discoverability problems.

Quick Reference Checklist

Use this checklist whenever you're capitalizing a book title:

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