In the 17th edition of the Chicago Manual of Style, §8.159, the following rules are given (among others) for headline-style capitalization:

  1. Capitalize the first and last words in titles and subtitles (but see rule 7), and capitalize all other major words (nouns, pronouns, verbs, adjectives, adverbs, and some conjunctions—but see rule 4).
  2. Lowercase the articles the, a, and an.
  3. Lowercase prepositions, regardless of length, except when they are used adverbially or adjectivally (up in Look Up, down in Turn Down, on in The On Button, to in Come To, etc.) or when they compose part of a Latin expression used adjectivally or adverbially (De Facto, In Vitro, etc.).
  4. Lowercase the common coordinating conjunctions and, but, for, or, and nor.

But then, in §8.160, the following example is given:

Four Theories concerning the Gospel according to Matthew (2,3)

In understand that the is lowercased because of Rule 2 and to is lowercased because of Rule 3, but why are concerning and according lowercased? Aren't these “major words”?

  • Helpful reminder: code-blocks here are exclusively for quoting code; please use *italics*, **bold** or >quotes.
    – Lordology
    Oct 12, 2019 at 20:44

2 Answers 2


There is an excellent online resource called Title Case Converter. It allows you to enter text, and it then shows you how it would be formatted in title case according to the major style guides.

It also provides an explanation for each word if you select that option.

Here is what it says about the phrase in the question, after selecting Chicago as the style guide to use:

  • Four is capitalized because it is the first word of the title.
  • Theories is capitalized because it is neither an article, a coordinating conjunction nor a preposition.
  • concerning is not capitalized because it is probably used as a preposition (as e.g. in “news concerning the election”). However, it can also be used as an adjective (“this is quite concerning to me”) or verb (“we should be concerning ourselves with that”), in which case it must be capitalized. As a rule of thumb, when “concerning” can be replaced with “regarding,” it is a preposition and must be lowercased.
  • the is not capitalized because it is an article.
  • Gospel is capitalized because it is neither an article, a coordinating conjunction nor a preposition.
  • according is not capitalized because it seems to be used as a preposition.
  • to is not capitalized because it is probably used as a preposition or particle. However, it can also be used as an adverb (“pull the door to”), in which case it must be capitalized.
  • Matthew is capitalized because it is the last word of the title or subtitle.

Note that there can be multiple reasons for a particular case. The case can also depend on the interpretation of how a word is being used, rather than just the word in isolation to everything else.

  • A marvellous tool, but surely belongs on meta? Oct 13, 2019 at 15:41
  • @EdwinAshworth I don't follow this comment. I used the online tool as a reference to support my answer in the same way that we routinely use online dictionaries and other sources of information. The tool itself isn't what's important—aside from it providing something objective; it's the content of the answer. Both the question and the answer belong here more than than they do on meta. Oct 13, 2019 at 15:52
  • choster has already explained the reason for the CMOS lowercasing, with references. A lot of the above is not relevant here. But this is a really good standard reference. Oct 13, 2019 at 16:02
  • @EdwinAshworth I provided my answer because the other one didn't explain how to know when concerning was being used as a preposition—as shown by the comment under it, indicating it wasn't clear. The feedback I gave does indicate how to make this distinction. Also, I feel it's more complete in terms of the overall question. There is no reason why there can't be multiple answers to the same question, each with their own references, if each author feels their own answer provides something different. (I do agree it's a good tool, however.) Oct 13, 2019 at 16:14

Concerning and according to are used as prepositions here, and are correspondingly lowercase in Chicago style.

In other common styles, any words longer than four letters get capitalized, and it is likely that the editors choose this example precisely to illustrate their position regarding prepositions.

  • Please excuse my ignorance, but how can I know when a verb is used as a preposition? When I parsed this sentence using Stanford parser I got "Four/NNP Theories/NNPS concerning/VBG the/DT Gospel/NN according/VBG to/TO Matthew/NNP", i.e."concerning" is a "Verb, gerund or present participle", how can I know that a given gerund is used as a preposition and therefore has to be lowercased?
    – yannis
    Oct 13, 2019 at 9:15

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.