• 3-minute read
• 5th December 2020

Writing Tips: The Basics of Punctuation in AP Style

AP style, the style set out in the Associated Press Stylebook, provides advice on many elements of writing. But what does it say about punctuation? Check out our guide to the basics of punctuation in AP style to find out.

Periods and Abbreviations in AP Style

AP style uses periods in the usual way at the end of a sentence. However, it does have a couple of requirements for how to punctuate abbreviations.

One is that you do not need a space between initials in a name:

C.S. Lewis and J.R.R. Tolkien were members of the Inklings. ✓

C. S. Lewis and J. R. R. Tolkien were members of the Inklings. ✘

The other is that you should use a period between each letter in two-letter abbreviations such as “U.K.,” “U.S.,” or “U.N.” For instance:

The U.N. headquarters in the U.S. is considered international territory. ✓

The UN headquarters in the US is considered international territory. ✘

There is no need to punctuate longer abbreviations, though (e.g., NASA, FBI, CBS).

Commas in Lists in AP Style

A serial (or Oxford) comma is a comma placed before the conjunction in a list of three or more items. In AP style, you should use one of these if at least one of the list items contains its own conjunction. For example:

Popular games include Scrabble, Monopoly, and Snakes and Ladders.

Here, the comma before “and” makes it clear that “Snakes and Ladders” refers to a single game (rather than two separate games called “Snakes” and “Ladders”).

However, you do not need this comma for lists of simple items:

Their pets include dogs, cats and birds.

In this case, for instance, we do not need the extra comma because it is already clear that “dogs,” “cats,” and “birds” are separate items in the list.

Possessive Apostrophes in AP Style

AP style has special rules for possessive apostrophes when a word ends in “s.” And how you indicate possession will depend on the type of word you’re using.

For singular common nouns that end in “s” (e.g., witness, bus, octopus), AP style suggests adding an apostrophe followed by a final “s” to indicate possession:

The witness’s testimony did not match his earlier statement.

When a singular proper noun ends in “s,” though, you only need an apostrophe:

Thomas’ shoelaces were untied.

The same applies for all plural nouns (common and proper) that end in “s”:

We’ll borrow the Joneses’ car for the weekend.

Have you seen the kittens’ toys?

Remember, then, that you need an extra “s” after a possessive apostrophe for a singular common noun that ends in “s.” In all other cases, including plural common nouns and singular proper nouns, just give the apostrophe after the final “s.”

Quotation Marks in AP Style

Finally, AP style typically follows American English conventions when it comes to punctuation marks. These are as follows:

• Use “double quote marks” for quotations.
• Only use ‘inverted commas’ for quotations within quotations.
• Always place periods and commas inside closing quote marks, even when they are not a part of the text being quoted.

If you are using UK or Australian English, though, you may want to ignore this advice! The AP Stylebook is written with American English in mind, so sometimes writers in other regions will need to adapt what it says to fit their own dialect.

And if you would like extra help to ensure your punctuation is perfect, why not submit a free 500-word trial document for our AP style experts to proofread today?