When should I use single quotation marks in APA Style?
Single quotation marks should be used "within double quotation marks to set off material that in the original source was enclosed in double quotation marks" (American Psychological Association, 2010, p. 92). In other words, if you have an internal quotation within a quotation, the internal quotation should be enclosed with single quotation marks. Do not use single quotation marks to "introduce a word or phrase used as an ironic comment, as slang, or as an invented or coined expression. Use quotation marks the first time the word or phrase is used; thereafter, do not use quotation marks" (p. 91). If you're using slang or an colloquial expression in your academic writing, please consider if it would be better to explain exactly what you mean instead of relying on an expression that your reader might not know or understand.
For more information on quotation marks, please see pages 91-92 in the Publication Manual of the American Psychological Association (American Psychological Association, 2010). For more information on how to introduce key words or terms in a work, please see "What are the APA Style rules for emphasizing words in text?".
American Psychological Association. (2010). Publication manual of the American Psychological Association (6th ed.). Washington, DC: Author.