How do I know when to capitalize a word?

Rules for capitalizing words are ones that have to be learned through memorization, repeated use, or consulting a resource like a dictionary or writing handbook. As with punctuation marks and other mechanics, the use of capital letters is a practice in written (and printed) rather than in spoken English.

According to some college surveys, nearly 50% of student papers contain capitalization mistakes (, and “unnecessary or missing capitalization” appears as error # 8 in the Top Twenty list. (Errors of capitalization did not occur on the original 1986 study “Twenty Most Common Errors.”)

It’s no wonder that errors of this sort have increased to the point they are appearing in these studies and surveys. Except for a few basic rules, the rules of capitalization may vary, not only in individual style guides, but also in different languages.

In addition, there has been an increase in more informal, or what is sometimes called casual text, writing in the mediums of text messaging, email, social networking, or instant messaging, in which people use lowercase and not any capitals.

This is true even with the pronoun I, which is one of the three consistent rules of capitalization:

  1. capitalize the pronoun I
  2. capitalize the first letter of every sentence
  3. capitalize the initial letter of proper nouns

Rule #1 is self-explanatory, notwithstanding the preponderance of the lowercase i in the casual writing mentioned above.

A capital letter at the beginning of a sentence, expressed in rule #2, is one of the markers of an independent clause, as we defined in an earlier post on punctuating compound sentences. The capital letter indicates the beginning of the sentence, just as a period or other mark of closing punctuation signals the end.

One of the capitalization errors identified in student writing had to do with names, or proper nouns, addressed in the rule #3. A proper noun names a specific item, which could be a person (Robert), a building (the Empire State Building), a city (New York City), a state (New York State), a country (Italy), and so on.

With the example New York State, however, we encounter one of those varying practices mentioned above. Depending on which style you follow, the name of the Empire State will be written as New York State (Gregg Reference Manual) or as New York state (Associated Press Stylebook).

Because the names of days, months, and holidays are proper nouns, they are capitalized, but seasons are not: Friday, May, Memorial Day, but spring or summer.

Proper adjectives are words made from proper nouns and are also capitalized. If we take the name of a country, such as the proper noun Italy (from the example above), the proper adjective is Italian. A common mistake is NOT capitalizing the proper adjective in the popular fast food, French fries (even though the food did not originate in the country of France). 

In addition, capitalization with titles of positions or organizations can cause people problems. 

The names of organizations are proper nouns, so they are capitalized: the Modern Language Association, the American Psychological Association.

When a title precedes the name, it requires capitalization: President Woodrow Wilson, General George Patton. In these situations, you’re using the label as a title, so it requires capitalization like any other ordinary title (Mr., Ms., or Dr.). If the title comes after the person’s name or if there is a “the” before the title, it is generally not capitalized: Mary Stuart, the vice president of finance, will present this year’s budget.

Dianna Booher points out an exception to this rule: “Capitalize position titles of state, federal, or international officials of high distinction, such as President of the United States or cabinet members. Mr. President, Madam Secretary” (Booher’s Rules of Business Grammar 2008).

Family names like mother, father, aunt, and uncle should be capitalized when they are used as proper nouns, but are in lower case when they are common nouns:  Aunt Frances is a biologist, but my mom is an astronaut.

Capitalization with Composition Titles

Style guides differ in their capitalization rules for titles of books, films, plays, and other works, though they generally agree that the first word and all nouns, proper nouns, adjectives, and verbs (including short ones, like is or are) should be capitalized. They disagree on how to handle articles, conjunctions, and prepositions, so you should follow the rules in the style guide you are using.

Another troubling area is the capitalization of acronyms.

An acronym, composed of the initial first letter of a word in a phrase, is usually capitalized. Some common acronyms include FBI for Federal Bureau of Investigation; CIA for Central Intelligence Agency; and AWOL for Absence Without Official Leave.

There are exceptions to capitalizing acronyms. Some have become so prevalent that the have become common nouns; for instance, radar (short for RAdio Detection And Ranging) and laser (Light Amplification by Stimulated Emission of Radiation). In these cases, the words in the original phrase were capitalized.

This is not always true of acronyms. The following example shows a spelled out phrase that is NOT capitalized:

The program’s graphical user interface was extremely user friendly

The program’s GUI was extremely user friendly.   (source:

Capitalization and Quotes 

The two previous posts dealt with quotations – preventing mechanical errors and preventing plagiarism by documenting and attributing quotes from sources.

When the quote is a complete sentence, the first word is capitalized:  “Don’t compromise yourself,” said Janis Joplin. “You are all you’ve got.”

The first word of partial quotes is not capitalized:  Tragedy is defined by Aristotle as “an imitation of an action that is serious and of a certain magnitude.” (examples from The Everyday Writer 215-216)

Capitalization for Emphasis

Finally, some writers use all capital letters (all caps) in a word or phrase to show emphasis. Such practice is generally discouraged. Not only is such text harder to read, but it can be perceived as “screaming” or “shouting.” To emphasize a word or phrase, the preferred format is to use italics.

There are many other capitalization rules and examples, but rather than trying to memorize them all, you might do better to understand the concepts behind capitalization and to have a reference or handbook to check for unusual or unfamiliar cases.  

(Additional material adapted from posts by Richard Nordquist,,, and

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