Editing Tip: Capitalization Rules

  • The choice to use a capital or lowercase letter is not always clear
  • On occasion, a sentence does not start with a capital letter
  • The first word after a colon can also be capitalized

It is widely known that each sentence in English starts with a capital (or uppercase) letter. Here are some other cases in which the choice to use a capital or lowercase letter may be less obvious.

Terms that start with a lowercase letter

First, terms that always contain an initial lowercase letter must retain their lowercase letter, even at the beginning of a sentence.

  • mRNA samples were collected.
  • pH values ranged from 3.0 to 5.8.

As described in a post elsewhere on AJE Scholar, this also applies to chemical names with an italicized lowercase introductory letter (e.g., cis-, trans-, ortho-, tert-, n-, or i-). In these cases, however, the first letter of the compound name (the root word) is treated like a standard word (i.e., capitalized at the start of a sentence).

  • tert-Butanol was added to the mixture.
  • BUT Additional tert-butanol was required to complete the reaction.

Sentences with a colon

The first word after a colon (:) can be capitalized if the word starts an independent clause, although this capitalization is not required. When several independent clauses follow a colon, each clause should be capitalized.

  • This study examines the following question: What is the precise deformation and stress map of the steel cords within a TBR tire under actual working conditions?
  • This study examines the following questions: What is the precise deformation and stress map of the steel cords within a TBR tire under actual working conditions? What are the effects of that deformation on tire performance? How can that deformation be diminished?
  • BUT: This study measures several parameters: height, frequency, and wavelength.

We hope that these hints will help you decide when to capitalize a word as you write. Please email us with any questions or comments. Best of luck!

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