Abbrs.

Abbreviations are useful because (a) they avoid excess repetition of phrases or names (especially when long or ungainly) and (b) they save space. Follow these tips:

• Insert the abbreviation (within parentheses) after the first use of the phrase or name. Before final submission, recheck the text to make sure the very first use was found.
• However, there is no need to provide an abbreviation if the term is used only two or three times in the paper.
• Especially in the abstract, where space is at a premium, do not give an abbreviation unless it is used at least twice.
• Do not add abbreviations to phrases or names in headings and subheads, whether in the Table of Contents or in the text.
• Note, however, that some abbreviations are given as words—“not labeled abbr”—in the 2005 edition of Merriam-Webster’s Collegiate Dictionary (see APA §4.24).
• The APA Publication Manual offers this important reminder: “Use only those abbreviations that will help you communicate with your readers. Remember, they have not had the same experience with your abbreviations as you have.”

The Writing Center website lists further considerations such as plurals, Latin abbreviations, and units of measure. For complete guidance, see the APA Publication Manual, §4.22, p. 106ff. 

Tim McIndoo, who has been a dissertation editor since 2007, has more than 30 years of editorial experience in the fields of medicine, science and technology, fiction, and education. When it comes to APA style, he says, "I don't write the rules; I just help users follow them."