Title Capitalization Rules

There are two basic styles for the capitalization of titles and headlines, sentence case and title case.
In sentence case, the first word and all proper nouns and proper adjectives are capitalized. All other words are lowercased (just like in a regular English sentence): Bank of America is missing out on Wall Street’s boom
In title case, the first word (and usually the last word) is capitalized, as well as all major words. Minor words are lowercased: Bank of America Is Missing Out on Wall Street’s Boom
However, there is no universal convention which words in a title are major and which are minor. Rather, there are various style guides which each have their own rules regarding title case. This page describes the title case rules of eight common style guides: the AMA Manual of Style, the AP Stylebook, the APA Publication Manual, the Bluebook, the Chicago Manual of Style, the MLA Handbook, the New York Times Manual of Style and Usage, and the Wikipedia Manual of Style. Also featured is a table with a comparison of these styles.
A different approach to title case can be found on the page Words to Capitalize in a Title, which specifies the correct capitalization for individual words. And, of course, the Title Case Converter offers a fully automatic conversion to title case, applying the rules of the style of your choice.
Cover of the AMA Manual of Style

AMA Title Case

  • Capitalize the first word of titles and subtitles
  • Capitalize major words
  • Do not capitalize coordinating conjunctions (and, but, for, nor, or, so, yet), articles, or prepositions of three or fewer letters
  • Do not capitalize to in infinitives
  • Do not capitalize the second part of a hyphenated compound in the following cases:
    • either part is a prefix or suffix (e.g., “Anti-inflammatory,” “System-wide”)
    • both parts together constitute a single word (which is listed in Merriam-Webster’s Collegiate Dictionary, Stedman’s or Dorland’s, e.g., “Short-term”)
  • Capitalize the second part of a hyphenated compound if both parts carry equal weight (e.g., “Cost-Benefit”)
  • Capitalize the first non-Greek letter after a lowercase Greek letter (e.g., “β-Blocker”)
  • Lowercase the first non-Greek letter after a capital Greek letter (e.g., “Δ-9-tetrahydrocannabinol”)
  • Capitalize the genus but not the species epithet

Source

The JAMA Network Editors. AMA Manual of Style. 11th ed. Oxford: Oxford University Press, 2020.

Commentary

What makes AMA style and complicated are the rules regarding hyphenated compounds. They also lead to nonintuitive results: Since “low-level” is listed in Merriam-Webster’s Collegiate Dictionary and “low-value” isn’t, these words are capitalized differently: “Low-level,” but “Low-Value.” On the other hand, being listed in Merriam-Webster’s does not automatically mean that the second part of a hyphenated compound is not capitalized; if both parts have equal weight, then the second part is capitalized after all. This is sometimes difficult to judge.
Cover of the Associated Press Stylebook

AP Title Case

  • Capitalize the first word and the last word of the title
  • Capitalize the principal words
  • Capitalize to in infinitives
  • Capitalize all words of four letters or more
  • Do not capitalize articles, conjunctions, and prepositions of three letters or fewer

Source

The Associated Press. The Associated Press Stylebook. 55th ed. New York: Basic Books, 2020.

Commentary

It should be noted that the rules above are the AP rules for composition titles (titles of books, movies, songs, poems etc.) For headlines, the AP Stylebook prescribes sentence case.
In previous editions of the AP Stylebook, it was not clear whether the rule to not capitalize short conjunctions only refers to coordinating conjunctions, or also includes subordinating conjunctions. The 2019 edition made it clear that short subordinating conjunctions like if are indeed not capitalized in AP style.
Cover of the Publication Manual of the American Psychological Association

APA Title Case

  • Capitalize the first word of a title or subtitle
  • Capitalize the first word after a colon, em dash, or end punctuation
  • Capitalize nouns, verbs, adjectives, adverbs, and pronouns
  • Capitalize all words of four letters or more
  • Do not capitalize articles, conjunctions, and prepositions of three letters or fewer
  • Capitalize the second part of hyphenated major words
  • Do not capitalize the second part of a Latin species name

Sources

American Psychological Association. Publication Manual of the American Psychological Association. 7th ed. Washington, DC: American Psychological Association, 2020.
Lee, Chelsea. “Title Case and Sentence Case Capitalization in APA Style.” APA Style Blog. March 9, 2012. Accessed September 1, 2018. http://blog.apastyle.org/​apastyle/​2012/​03/​title-case-​and-​sentence-​case-​capitalization-​in-​apa-​style.html
McAdoo, Timothy. “How to Format Scientific Names of Animals.” APA Style Blog. February 15, 2017. Accessed September 1, 2018. http://blog.apastyle.org/​apastyle/​2017/​02/​-how-to-​format-​scientific-​names-​of-​animals.html

Commentary

While all other styles discussed on this page always capitalize the last word of a title, APA style has no such rule, which means that prepositions at the end of titles must be lowercased (e.g., “Service You Can Count on”).
The rule to lowercase short conjunctions includes subordinating conjunctions. The 7th edition of the APA Publication Manual explicitly lists as and if as conjunctions to be lowercased.
The Publication Manual does not explicitly state how to in infinitives should be handled, but it uses a lowercase to in its own headings, for example, “Strategies to Improve Your Writing” in chapter 4.
Cover of the Bluebook

Bluebook Title Case

  • Capitalize the first word of a heading or title and the first word after a colon
  • Capitalize all words except articles, conjunctions, or prepositions of four letters or fewer

Source

Harvard Law Review, Columbia Law Review, and Yale Law Review. The Bluebook: A Uniform System of Citation. 21st ed. Cambridge: Harvard Law Review Association, 2020.

Commentary

While the Bluebook does not explicitly mention whether or not the to in infinitives should be capitalized, it contains several example titles that show that it should not be capitalized, for example, “Using Private Schools to Promote Public Values” in chapter 16.4.
Furthermore the Bluebook does not make it clear whether the rule to not capitalize short conjunctions also refers to subordinating conjunctions such as if or as. Judging from past article titles in The Harvard Law Review, this does not seem to be the case (e.g., “We Couldn’t Kill the Internet If We Tried”).
Cover of the Chicago Manual of Style

Chicago Title Case

  • Capitalize the first and last words of titles and subtitles
  • Capitalize nouns, pronouns, verbs, adjectives, adverbs, and some conjunctions
  • Do not capitalize articles and prepositions (regardless of length), except for prepositions that are part of Latin expressions used adjectivally or adverbially (e.g., “In Situ”)
  • Do not capitalize the conjunctions and, but, for, or, and nor
  • Do not capitalize to in infinitives
  • Do not capitalize as in any grammatical function
  • Do not capitalize the part of a proper name that would be lowercased in text (e.g., “Vincent van Gogh”)
  • Do not capitalize the second part of a Latin species name, even if it is the last word of the title or subtitle
  • In hyphenated compounds, capitalize the first element and subsequent words that are not articles, prepositions, coordinating conjunctions, or modifiers following musical key symbols (e.g., “Symphony in F-sharp Major”); however do not capitalize the second word if the first element is a prefix that could not stand by itself (e.g., “Ex-wife”), unless it is a proper noun or proper adjective.

Source

The University of Chicago Press Editorial Staff. The Chicago Manual of Style. 17th ed. Chicago: University of Chicago Press, 2017.

Commentary

The title case rules of the Chicago Manual of Style are more exhaustive than all others, and they feature a few peculiarities: All other styles (except for the New York Times) lowercase all seven coordinating conjunctions, but only five are lowercased in Chicago style, namely and, but, for, nor, and or, whereas yet and so are capitalized.
On the other hand, as is always lowercased in Chicago style, which is sensible, because it avoids the necessity of determining the grammatical function of this word.
Cover of the MLA Handbook

MLA Title Case

  • Capitalize the first word and the last word of titles and subtitles
  • Capitalize nouns, pronouns, verbs, adjectives, adverbs, and subordinating conjunctions
  • Do not capitalize articles, prepositions (regardless of length), and coordinating conjunctions
  • Do not capitalize to in infinitives
  • Capitalize principal words that follow hyphens in compound terms
  • Do not capitalize the word that follows a hyphenated prefix if the prefix combined with the word is listed without a hyphen in a dictionary (e.g., “Anti-tumor,” but “Anti-Intellectual”)

Source

Modern Language Association of America. MLA Handbook. 9th ed. New York: Modern Language Association of America, 2021.

Commentary

MLA style is similar to Chicago style insofar as both lowercase all prepositions, regardless of length. However, MLA style treats all coordinating conjunctions alike and does not have special rules for as. The rules regarding hyphenated words seem unwieldy since they require consulting a dictionary, and furthermore can lead to different results depending on which dictionary is used.
Cover of the New York Times Manual of Style and Usage

New York Times Title Case

  • Capitalize nouns, pronouns, and verbs
  • Capitalize all words of four or more letters
  • Capitalize no, nor, not, off, out, so, and up
  • Do not capitalize a, and, as, at, but, by, en, for, if, in, of, on, or, the, to, v., vs., and via, except when used as adverbs
  • Capitalize for if it takes the place of a verb meaning “support” or “advocate”
  • In hyphenated compounds, do not capitalize the second part if it follows a prefix of two or three letters and if the hyphen separates doubled vowels (e.g., “Co-operation”). Otherwise, capitalize the second part (e.g., “Co-Author”).

Source

Siegal, Allan M., Connolly, William G., Corbett, Philip B., and New York Times Company. The New York Times Manual of Style and Usage. 5th ed. New York: Three Rivers Press, 2015.

Commentary

The New York Times style is unique among the styles discussed here since not all 2- and 3-letter preposition are lowercased in this style. Instead, short words to capitalize and to lowercase are explicitly listed. This results in the prepositions off, out, and up being capitalized in New York Times style while they would be lowercased in any other style.
Taken verbatim, the New York Times rules would mean that in and on should be lowercased when used as adjectives, but that is probably not the intended meaning, and evidence suggests that they are capitalized in that grammatical function.
Wikipedia logo

Wikipedia Title Case

  • Capitalize the first word and last word of the title
  • Capitalize verbs, nouns, pronouns, adjectives, adverbs, and subordinating conjunctions
  • Capitalize prepositions of five letters or more
  • Capitalize the first word in a compound preposition (e.g., “Out of”)
  • Do not capitalize articles, prepositions of four letters or fewer, and coordinating conjunctions
  • Do not capitalize to in infinitives
  • For hyphenated words, follow the majority usage in independent, reliable sources

Source

Wikipedia:Manual of Style/Titles#Capital_letters.” Wikipedia. Accessed September 1, 2018. https://en.wikipedia.org/​wiki/​Wikipedia:​Manual_of_Style/​Titles​#Capital_letters.

Commentary

In Wikipedia style, preposition with up to four letters are lowercased, which means that Wikipedia style represents a compromise between journalistic styles, where only short preposition with up to three letters are lowercased (e.g., AP) and academic styles, where all prepositions are lowercased, regardless of length (Chicago, MLA).
The Wikipedia rules are detailed and clearly specify how to capitalize a multitude of cases, with the exception of hyphenated compounds, for which the rules instruct to follow external sources. This seems unusual.

Style Guide Comparison

The following table provides a comparison of the title case rules of the six style guides supported by this website. The following symbols are used: stands for “capitalize,” stands for “lowercase,” and “” means that the style guide does not have a rule for the word or case in question.
AcademiaJournalism
CMOSMLABBAPAAMAAPNYTWP
first word
last word
nouns
pronouns
verbs
adjectives
adverbsas
but
to
other
articles
prepositions1 letterv.
2 lettersat
by
in
of
on
up
to
other
3 lettersbut
for /
off
out
via
other
4 lettersfrom
into
unto
with
other
5+ lettersany
coordinatingfor
conjunctionsand
nor
but
or
yet
so
subordinatingas
conjunctionsif
other
“to” in infinitives
second part of species names()()()