When using title case, capitalizing hyphenated words can be quite difficult. The various style guides have many rules on this topic, and unfortunately these rules are not in agreement. While there are similarities and common rules, there are also many differences, and several styles have rules that exist only in that style. However, I will provide a comprehensive overview in this article.
Hyphenated Compound Words
A compound word consists of two or more regular words that have been combined to create a new word. There are closed compound words (eye + ball = eyeball), open compound words (eye + candy = eye candy), and hyphenated compound words (eye + catcher = eye-catcher). In the context of this article, we are only interested in the latter. First let’s see what the various style guides say about hyphenated compound words. By the way, words with prefixes (anti-, co-, ex-, non-, etc.) are not covered here; those will be discussed in the next section.
The AP Stylebook entry on composition titles doesn’t have any rules for hyphenated words, but one of the examples given is “The Star-Spangled Banner.” An answer in the Ask the Editor section of the AP website confirms the capitalizations “Follow-Up” and “All-In,” and provides the guidance: “Capitalize both parts in an all-caps, or primary-word caps, headline style.” Another answer deals with a compound word with more than two parts (“Step-by-Step”) and shows that minor words are not capitalized in such compounds.
The APA Publication Manual says that major words should be capitalized, “including the second part of hyphenated major words.” This guideline seems to cover only hyphenated words with two parts, but checking titles of articles that were published in APA journals shows that minor words in longer hyphenated compounds are lowercased (e.g., “All-or-None,” “Trial-by-Trial”).
The Bluebook doesn’t address the capitalization of hyphenated words explicitly, but there are several examples throughout the book, including “Fifty-Third” and “Case-by-Case.”
The Chicago Manual of Style (CMOS) states that the first element of a hyphenated compound should always be capitalized, and any subsequent elements that are not articles, prepositions, or coordinating conjunctions. This includes spelled-out numbers, e.g., “Twenty-One.” An exception is made for modifiers following musical key symbols; those must be lowercased (e.g., “F-sharp”).
The MLA Handbook prescribes capitalizing “all principal words, including those that follow hyphens in compound terms.” Musical note modifiers like “flat” or “sharp” are not explicitly mentioned, but an example shows that they are lowercased, just like in Chicago style: “Piano Trio in E-flat Major D 929”
The New York Times Manual of Style and Usage says that “both parts” of a hyphenated compound should be capitalized. This raises the question how hyphenated compounds with more than two elements should be handled, but there are plenty examples from actual headlines available that show that, for example, “Back-to-School,” “Make-or-Break.”
The Wikipedia Manual of Style has the following rule: “Follow the majority usage in independent, reliable sources for any given subject (e.g. The Out-of-Towners but The History of Middle-earth). If neither spelling is clearly dominant in sources, default to lowercase after a hyphen […]”
The AMA Manual of Style states that the second part of a hyphenated compound should not be capitalized if it is a suffix (e.g., -type, -elect, -designate, -wide), or if both parts together constitute a single word (e.g., “Short-term,” “Follow-up,” “Low-level”). To determine the latter, you need to check if it’s listed in Merriam-Webster’s Collegiate Dictionary or Stedman’s or Dorland’s medical dictionary. If a compound is temporary (i.e., not listed in a dictionary), then the second part is capitalized (e.g., “Low-Value”). The second part must also be capitalized if the compound is listed in a dictionary, but both parts carry equal weight (e.g., “Cost-Benefit”).
The AP, APA, Bluebook, Chicago, MLA, and New York Times guidelines for hyphenated compounds vary in detail, and in some cases it’s necessary to refer to examples to get a complete picture. Still, it becomes apparent that there is a standard rule shared by all these styles: The first word in a hyphenated compound is capitalized, and the subsequent words are lowercased if they are minor words (in the respective style), and capitalized else. The Wikipedia Manual of Style advises to follow the usage in outside sources. Since these sources quite likely also follow this standard rule, we can assume that the standard rule (usually) also applies to the Wikipedia style.
This leaves AMA style as an outlier. Capitalizations like “Hands-on,” “Long-term” or “President-elect” can only be found in this style. Since the rules require consulting a dictionary, and/or judging whether both parts of a hyphenated word carry equal weight, using this style can be tricky.
Here a few examples, first for AP, APA, Bluebook, Chicago, MLA, New York Times, and Wikipedia style:
Using State-of-the-Art Technology to Create High-Quality Products
(NB: In AP style, it is “To Create,” see Is To Capitalized in a Title?)
Drive-In Movie Theaters Are Making a Comeback
A Long-Term, Double-Blind, Placebo-Controlled Crossover Trial
In AMA style, the first example stays unchanged, but the others would look as follows:
Drive-in Movie Theaters Are Making a Comeback
A Long-term, Double-blind, Placebo-Controlled Crossover Trial
(“Drive-in,” “long-term,” and “double-blind” are listed in Merriam-Webster’s, but “high-quality” and “placebo-controlled” are not.)
While compound words are created by combining two or more regular words, there is also the possibility to add a prefix to a regular word in order to create a new word (e.g., ex + wife = ex-wife). These prefixes (typical examples are anti-, co-, de-, ex-, non-, pre- and re-) cannot stand by themselves, which differentiates prefixed words from compound words, and many styles have separate rules for these two types of hyphenated words. (Of course this only applies when there is a hyphen—often these prefixes are added without one.) Here’s an overview of the individual rules for prefixed words:
The AP Stylebook does not address the capitalization after a prefix, but the Ask the Editor section on its website has several entries regarding this issue. Unfortunately, the answers are not completely consistent, but the majority of the answers advises capitalizing the word after the prefix when used in a title, e.g. “Non-Medical,” “Anti-Bribery,” “Non-Governmental.”
The APA Publication Manual doesn’t cover prefixed words either, but the APA blog makes clear that only the first letter of a prefixed word is capitalized. This is illustrated by the example “Pre-existing” which is contrasted to the compound word “Self-Report.”
The AMA Manual of Style states that the word after a hyphenated prefix is not capitalized. Unlike any other style guides, the AMA Manual also considers self- to be a prefix, so any word following it is not capitalized (e.g., “Self-report”).
The Bluebook doesn’t address hyphenated words at all, but has two examples of prefixed words, “Quasi-Spousal” and “Non-Named,” that show that the word after a prefix is capitalized.
The Chicago Manual of Style says that if the first element of a hyphenated word is a prefix or combining form, then the second element is not capitalized, unless it is a proper noun or proper adjective.
The MLA Handbook states that the word following a hyphenated prefix should not be capitalized if the combination of prefix and word is listed in a dictionary without a hyphen. For example, Merriam-Webster’s lists “antitumor,” but not “antiintellectual,” only “anti-intellectual,” so these two words are capitalized “Anti-tumor” and “Anti-Intellectual” in MLA style.
The New York Times Manual of Style and Usage provides the following rules: If the prefix has four or more letters, capitalize the next word (e.g., “Anti-Inflammation”). If the prefix has two or three letters, lowercase the word after the hyphen if the hyphen is used to separate doubled vowels or to clarify pronunciation (e.g., “Co-operation”). Otherwise, capitalize it (e.g., “Co-Author”).
The Wikipedia Manual of Style has no specific rules regarding the capitalization after a prefix, so its general guidance for capitalizing hyphenated words applies: “Follow the majority usage in independent, reliable sources.”
The rules for prefixed words are more varied than for hyphenated words. The eight styles discussed here can be divided into four groups.
- In AP and Bluebook style, the word after a prefix is always capitalized (e.g., “Pre-Existing”).
- In Chicago, AMA, and APA style, the word after a prefix is lowercased (e.g., “Pre-existing”), unless it is a proper noun or proper adjective (e.g., “Pre-Christian”). Unlike the other two styles, AMA style treats self- as a prefix.
- In MLA style, words after a prefix are sometimes capitalized and sometimes not, depending on whether the complete word can be found in a dictionary without a hyphen (“Pre-Existing,” but “Pre-owned”).
- New York Times style also capitalizes the word after a prefix in some cases and not in others, but here the decision depends on the length of the prefix and whether the hyphen separates doubled vowels (“Pre-existing”, but “Pre-Owned”).
Wikipedia does not have explicit rules for prefixed words, but for practical purposes, I’d put Wikipedia style in group 2 with the scientific styles, since the character of Wikipedia is more scientific than journalistic.
The following example illustrates the different results:
Are Species Co-Occurrences on Islands Non-Random?
AMA, APA, Chicago (and Wikipedia):
Are Species Co-occurrences on Islands Non-random?
Are Species Co-Occurrences on Islands Non-random?
New York Times:
Are Species Co-occurrences on Islands Non-Random?
Single Letter Prefixes
A prefix can also consist of a single letter, as in “e-commerce,” “T-shirt” or “X-ray.” Almost all styles handle such prefixes just like the prefixes discussed previously.
AMA style seems to be the only exception: The AMA Manual states that the word following a stand-alone capital letter is capitalized (illustrated by the example “C-Reactive”), while words after prefixes like co- or non- are not capitalized.
In APA style on the other hand, the word following a single-letter prefix is not capitalized, as evidenced by the example “E-book” in a heading of their blog.
The same applies to the Chicago Manual of Style, which features “E-mail” as an example for handling words after a hyphenated prefix.
The MLA Handbook uses “E-Book” on page 316 and “E-mail” on page 337, which is consistent with their rules, since Merriam-Webster’s lists “email,” but not “ebook.”
In actual New York Times headlines we find “E-Bike,” “T-Shirt,” and “X-Ray,” which indicates that the word following a single-letter prefix is always capitalized in that style.
Since there is no evidence to the contrary, I think it is valid to assume that AP, Bluebook, and Wikipedia style also make no distinction between single-letter prefixes and longer prefixes.
This means we can group the styles into three classes:
AMA, AP, Bluebook, New York Times: capitalize the word after a single-letter prefix:
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APA, Chicago (and Wikipedia): do not capitalize the word after a single-letter prefix:
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MLA: capitalize the word after a single-letter prefix unless the complete word is listed in a dictionary without a hyphen:
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Sometimes the prefix a- is used before present participles, as for example in “a-runnin’.” This usage, which is called a-prefixing, is archaic or dialectical, but it does occur in some song and movie titles. None of the style guides addresses this case explicitly, so the rules established in the previous section apply. These words are never listed in a dictionary without a hyphen, so there are only two classes instead of three:
AMA, AP, Bluebook, MLA, New York Times: capitalize the word following a-:
The Times They Are A-Changin’
APA, Chicago (and Wikipedia): do not capitalize the word following a-:
Don’t Come Home A-drinkin’
Train Kept A-rollin’
Greek Letter Prefixes
The AMA Manual has special rules for words following Greek letters:
Lowercase the first non-Greek letter after a capital Greek letter:
The Effect of Δ-9-tetrahydrocannabinol on Sleep
Capitalize the first non-Greek letter after a lowercase Greek letter:
Glucagon Therapy for β-Blocker Overdose
Other Words with Hyphens
Not all words with hyphens are compound words or prefixed words. Hyphens also occur in proper names, and there are proper names where either the first or second part is lowercase (e.g., Bashar al-Assad, Kim Jong-un). Naturally, this does not only apply when these names occur in regular text, but also when they occur in titles or headlines:
The Best Bong Joon-ho Movies
Hyphens are also sometimes used before suffixes like -ish and -y, especially in made-up words that cannot be found in a dictionary. Of course, these suffixes must not be capitalized:
Are We All a Little Stalker-ish?
Organic Tomato-y Pasta with Vegetables
(Capitalizing these words does not really pose a problem for people; but simple title capitalization tools do not handle such words correctly. The Title Case Converter, however, does.)
Some of the title case styles have more complex rules regarding hyphenated words than others. If you are free to choose a style (see Which Title Case Style Should You Use?), you may want to factor that in and perhaps avoid a style that requires consulting a dictionary.
On the other hand, you can leave the capitalization to the Title Case Converter, which supports all the various rules of all the styles discussed here, including those that depend on dictionaries. Give it a try!