As a freelance academic editor, I spend a lot of my time learning various style guides. I am familiar with the big ones (AMA, APA, Chicago, MLA), but clients often have their own in-house style guides as well. They might follow Chicago style up to a point but also borrow elements from APA style. Learning all these rules (and exceptions to the rules) can be difficult. I often have to rely on well-written style sheets and look things up even if I’m fairly certain I know the answer to something.

APA style in particular seems to be controversial among editors—you either love it or you hate it. I happen to love it, but I know there are some quirks that can throw editors off. Here I’ve compiled a list of 10 style rules that I’ve struggled with in the past. Please feel free to share your own pet peeves!

Publication Manual of the American Psychological Association, Sixth Edition
APA Style Blog

1. Anchors of a scale

Italicize anchors of a scale; do not use double quotation marks or other formatting.

Ratings ranged from 1 (poor) to 5 (excellent)

2. Back-to-back parentheses

Do not use parentheses back to back.


(autism spectrum disorder; Smith & Wilson, 1994)


(autism spectrum disorder) (Smith & Wilson, 1994)

3. Compounds with comparative or superlative adjectives

Do not hyphenate a compound including a comparative or superlative adjective.

better written paper

higher order learning

lower scoring students

4. Slash

Do not use a slash for simple comparisons. An en dash is best used instead.

test–retest reliability

5. Capitalization in titles and headings

Capitalize major words in titles of books and articles within the body of a paper. Conjunctions, articles, and short prepositions are not considered major words; however, capitalize all words of four letters or more.

Attitudes Toward Mental Health Workers

Ultrasonic Vocalizations Are Elicited From Rat Pups

6. Approximations of numbers

In APA style, numerals are generally used to express numbers that represent time, dates, ages, and scores and points on a scale. However, use words for approximations of numbers of days, months, and years.

about three months ago

approximately five years old

7. Numbers in abstracts

Use numerals to express numbers in the abstract of a paper or in a graphical display within a paper.

8. Capitalization for racial and ethnic groups

Racial and ethnic groups are designated by proper nouns and are capitalized. Therefore, use Black and White instead of black and white.

Thirty-four Black adolescents participated in the study.

There were five White students in the class.

9. Brackets

Do not use brackets to set off statistics that already include parentheses.


The results were statistically significant, F(1, 32) = 4.37, p = .045.


The results were statistically significant (F[1, 32] = 4.37, p = .045).


The results were statistically significant [F(1, 32) = 4.37, p = .045].

10. References with the same authors and same year

This is a tricky rule to learn in APA style. Many other style manuals use “a” and “b” designations when a reference has the same first author and the same publication year. In APA style, however, knowing how to cite these references in the text can get complicated.

Consider the following examples:

Koriat, A. (2008a). Easy comes, easy goes? The link between learning and remembering and its exploitation in metacognition. Memory & Cognition, 36, 416–428.

Koriat, A. (2008b). Subjective confidence in one’s answers: The consensuality principle. Journal of Experimental Psychology: Learning, Memory, and Cognition, 34, 945–959.

Pretty straightforward, right? In the text, the citations would be (Koriat, 2008a) and (Koriat, 2008b).

But if you have multiple author names in a reference, the author names must be exactly the same and in the same order to use this method.

Consider the following examples:

Marewski, J. N., Gaissmaier, W., & Gigerenzer, G. (2010). Good judgments do not require complex cognition. Cognitive Processing, 11, 103–121.

Marewski, J. N., Gaissmaier, W., Schooler, L. J., Goldstein, D. G., & Gigerenzer, G. (2010). From recognition to decisions: Extending and testing recognition-based models for multi-alternative inference. Psychonomic Bulletin & Review, 17, 287–309.

The first in-text citations for these would be (Marewski, Gaissmaier, & Gigerenzer, 2010) and (Marewski, Gaissmaier, Schooler, Goldstein, & Gigerenzer, 2010).

The subsequent in-text citations would be (Marewski, Gaissmaier, & Gigerenzer, 2010) and (Marewski, Gaissmaier, Schooler, et al., 2010).

If you use (Marewski et al., 2010) for subsequent in-text citations, it would be impossible to know which one you mean. Following APA style, you need to spell out the author names so the reader can tell them apart.

Let’s look at a couple more:

Shillingsburg, M. A., Frampton, S. E., Wymer, S. C., & Bartlett, B. (2016).

Shillingsburg, M. A., Gayman, C. M., & Walton, W. (2016).

These both have a publication year of 2016. The citations would be written as follows in the text:

First instance:

(Shillingsburg, Frampton, Wymer, & Bartlett, 2016)

(Shillingsburg, Gayman, & Walton, 2016)

Second instance:

(Shillingsburg, Frampton, et al., 2016)

(Shillingsburg, Gayman, & Walton, 2016)

[Note that (Shillingsburg, Gayman, et al., 2016) should not be used because et al. is plural and cannot represent only one name.]

What other rules of APA style do you struggle with? Did I miss any other quirks?

9 thoughts to “10 Quirky Rules of APA Style

  • Laura Ripper

    Thanks, Denise – saving this for future reference! The rule on citing works by the same lead author with different co-authors in the same year is one I always have to look up. Nice to have it explained so clearly here!

    • Denise Foster

      I’m glad it’s helpful! Ugh, that one is the worst. Sometimes you can get away with “Smith et al., 2010a” or whatever, but not in APA!

  • Cherry-Ann M Smart

    Denise, I don’t think your No. 10 is correct based on APA rules…See 6.12 and 6.16 APA 6th edition. Bless.

    • Denise Foster

      Which parts are you referring to? I’d be happy to clarify my post if I’m incorrect. According to 6.12:

      Exception: If two references of more than three surnames with the same year shorten to the same form, cite the surnames of the first authors and of as many of the subsequent authors as necessary to distinguish the two references, followed by a comma and et al.

      See also

  • Ceil Goldman

    So well done and helpful! Bravo and many thanks.

  • Ronda Roaring

    Thanks, Denise, for this post. Every style seems to have its own quirks. Keeping the quirks straight can be a real challenge. I’m glad CMOS has decided to cite AGAINST using et al.

  • Laura Thompson

    Thanks so much for this. I especially appreciate the brackets and parenthesis content. The last dissertation I edited was rife with statistics, and I had a difficult time finding answers. It seems there is always a situation not covered by the APA manual! 🙂

    • Denise Foster

      You’re welcome! I’m glad you found it helpful.


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