Current Students Info

Writing tip: Back to basics with periods

March 23, 2016
Source: Crossroads

A period ends a complete sentence that provides a statement or instruction, which is a straightforward function. However, things get a little more complicated when authors have to decide where to place periods after quotations, what spacing to use after a period, and when not to use a period.

Inside or outside punctuation with quotations

Confusion regarding whether a period should appear inside or outside closing quotation marks is usually caused by conflicting styles between American and British authors. The American style presents the period inside the quotation marks, whereas the British style places the period outside the quotation marks (Chelsea, 2011, para. 3). According to the APA Style rules, the closing period should appear inside in the quotation marks (para. 3); e.g., most participants chose “yes.”

If the quoted text is a direct quotation of 39 words or fewer and therefore has a citation after the closing quotation marks, the period appears after the citation. For example, “if the quotation appears at the end of a sentence, close the quoted passage with quotation marks, cite the source in parentheses immediately after the quotation marks, and end with a period or other punctuation outside the final parenthesis” (American Psychological Association, 2010, p. 92).

If the quotation is 40 words or longer and will be formatted as a block quotation, place the period at the end of the quotation and before the citation. For example:

Compositors―people who layout printed material with type―made the original rule that placed periods and commas inside quotation marks to protect the small metal pieces of type from breaking off the end of the sentence. The quotation marks protected the commas and periods. In the early 1900s, it appears that the Fowler brothers (who wrote a famous British style guide called The King’s English) began lobbying to make the rules more about logic and less about the mechanics of typesetting. They won the British battle, but Americans didn’t adopt the change. (Fogarty, 2013, p. 1)

For more information on the APA Style rules regarding inside or outside punctuation, please refer to “Punctuating Around Quotation Marks” from the APA Style Blog.

Spacing after a period

In the body of your work, you can use either one or two spaces after a period, but please do so consistently; see Spaces after a period? for more information. To check for consistent spacing, take advantage of Microsoft Word’s grammar and style check, which will look for one or two spaces between sentences:


For instructions on turning on Word's grammar and style check, please see Help From MS Word: Grammar and Style Check.

Within references, a period should always be followed by one space (American Psychological Association, 2010, p. 87).

When not to use a period

According to the APA Style rules, periods should not be used in the following instances:

  • After a URL “to prevent the impression that the period is part of the URL. This is not a style issue but a retrieval issue” (American Psychological Association, 2010, p. 192). This logic would also apply to not providing a period after a DOI.
  • After “metric or nonmetric measurement abbreviations” (p. 88) (e.g., cm, min). Use a period when abbreviating inches (in.) because without the period, “in” could be misunderstood (p. 88).
  • After state abbreviations, capitalized abbreviations, or acronyms (p. 88). Following this logic, abbreviations for Canadian provinces should not be followed by a period.

Do you have questions about using periods in your text? Please contact the Writing Centre as we’d be pleased to assist you.

Theresa Bell
Writing centre coordinator


American Psychological Association. (2010). Publication manual of the American Psychological Association (6th ed.). Washington, DC: Author. 

Chelsea, L. (2011, August 11). Punctuating around question marks [Blog post]. Retrieved from

Fogarty, M. (2013, December 23). How to use quotation marks [Blog post]. Retrieved from