Have you ever wondered while writing how to capitalize that book title, or how to write an address, or when to spell out a number? There are many ways you can write things, so how do you decide? Luckily, some pretty smart people already thought about all of these possible situations and put together handy style guides. A style guide is a written guide for exactly how to use words and punctuation and grammar in different situations. When you have multiple writers and editors working on a project it’s useful to have one source of “truth” for how you’re going to write things.

The style guide you use depends on the type of writing you’re doing. News publications have different style guides from academic journals and creative writing. A publication can even have a personal style guide with rules that apply specifically to it. Let’s go over some of the most widely used style guides and their most common rules.

AP Style

The Associated Press (AP) Stylebook is most commonly used by news publications. AP style provides guidelines for punctuation, grammar, spelling and language usage. The overall principles that guide these rules are consistency, clarity, accuracy and brevity. Since it is serving news organizations that provide information to a large population another goal is to avoid stereotypes and unintentionally offensive language.

To access the thousands of entries in the AP Stylebook, you can buy a hardcopy of the book, or you can access it online at the AP Stylebook website.

If you want to write using AP style, here are some big rules to get you started: (Source: AP Style | Purdue Writing Lab)


For ages, always use figures. If the age is used as an adjective or as a substitute for a noun, then it should be hyphenated. Don’t use apostrophes when describing an age range. Examples: A 21-year-old student. The student is 21 years old. The girl, 8, has a brother, 11. The contest is for 18-year-olds. He is in his 20s.

Books, Periodicals, Reference Works and Other Types of Compositions

Use quotation marks around the titles of books, songs, television shows, computer games, poems, lectures, speeches and works of art. Examples: Author Porter Shreve read from his new book, “When the White House Was Ours.” They sang “The Star-Spangled Banner” before the game.

Do not use quotations around the names of magazine, newspapers, the Bible or books that are catalogues of reference materials. Examples: The Washington Post first reported the story. He reads the Bible every morning.

Do not underline or italicize any of the above.


Always use a person’s first and last name the first time they are mentioned in a story. Only use last names on second reference. Do not use courtesy titles such as Mr., Mrs., Miss or Ms. unless they are part of a direct quotation or are needed to differentiate between people who have the same last name.


Never begin a sentence with a figure, except for sentences that begin with a year. Examples: Two hundred freshmen attended. Five actors took the stage. 1776 was an important year.

Use roman numerals to describe wars and to show sequences for people. Examples: World War II, Pope John Paul II, Elizabeth II.

For ordinal numbers, spell out first through ninth and use figures for 10th and above when describing order in time or location. Examples: second base, 10th in a row. Some ordinal numbers, such as those indicating political or geographic order, should use figures in all cases. Examples: 3rd District Court, 9th ward.

For cardinal numbers, consult individual entries in the Associated Press Stylebook. If no usage is specified, spell out numbers below 10 and use figures for numbers 10 and above. Example: The man had five children and 11 grandchildren.

When referring to money, use numerals. For cents or amounts of $1 million or more, spell the words cents, million, billion, trillion etc. Examples: $26.52, $100,200, $8 million, 6 cents.


Use a single space after a period.

Do not use commas before a conjunction in a simple series. Example: In art class, they learned that red, yellow and blue are primary colors. His brothers are Tom, Joe, Frank and Pete. However, a comma should be used before the terminal conjunction in a complex series, if part of that series also contains a conjunction. Example: Purdue University's English Department offers doctoral majors in Literature, Second Language Studies, English Language and Linguistics, and Rhetoric and Composition.

Commas and periods go within quotation marks. Example: “I did nothing wrong,” he said. She said, “Let’s go to the Purdue game.”

APA Style

American Psychological Association (APA) Style is primarily used for manuscripts from writers and students in the Social Sciences (such as Psychology, Linguistics, Sociology, Economics, and Criminology), Business and Nursing. By using this established style you’re helping your readers to find information that is formatted in an expected style.

APA style covers a broad range of considerations from page margin width to language choice and things to avoid. The basics of writing in APA style are concerned with relating the results of your experiment in a clear and direct manner. Flowery language and passive voice are discouraged. For a full explanation of writing style you can consult the The Publication Manual of the American Psychological Association at your library, or you can look at an online resource like the Purdue Writing Lab.

The other important distinction of APA style is the citation format. As a researcher you’re going to want to credit all of your sources accurately, either in in-text citations, or in footnotes. Take a look at the Purdue Writing Lab for examples of different types of citations.

Chicago Manual of Style

The Chicago Manual of Style (CMOS) is another academic style guide that is most commonly concerned with citations. There are two styles of citation acceptable in CMOS: the notes and bibliography system and the author-date system. If you’re in the humanities, the notes and bibliography system is preferred. In this system, sources are cited using numbered footnotes and endnotes, and each note corresponds to a superscript number in the text. Then all of the sources are usually listed in a separate bibliography.

If you’re in the sciences and not using APA style, you might be using the CMOS author-date system. Sources are briefly cited in the text with the author’s last name and year of publication in parentheses. The in-text citation matches up to a full bibliography.

For a full explanation of writing style within the Chicago Manual of Style, you can take a look at a hardcopy at your library, or access it online.

So does that clear things up for you, or are you even more tempted to procrastinate on your next writing project? Don’t worry about memorizing all of these style rules. Just pick the style that is most appropriate for your project and pull up a good online guide. You’ll be following those style rules in no time.