• 3-minute read
  • 3rd September 2023

What to Do with “et al.”

As you are most likely aware, “et al.” is used to save writing out multiple authors’ names in various types of referencing styles.

Exactly when and how it is used depends on the referencing style, but there are some issues associated with its use that, as a proofreader, you should keep an eye out for.

Launch the microlearning module below to learn more about using et al. and to test your knowledge using our interactive quiz.


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Alternatively, read on for a text-only version of the microlearning.

Top Five et al. Rules

Here are the things you should always remember about et al.:

  • It is always et al. (not et. al, etal, et. al. or any other variation).
  • The use of et al. automatically means that the associated verbs, pronouns etc will need to agree with the plural (“Jackson et al. (2020) have studied the problem. They suggest that…”). MS Word will not point this out to you in a grammar check, so be careful!
  • As a Latin term in common use, you do not need to italicize et al. unless a style guide requires that you do so. Notably, IEEE italicizes et al.
  • Et al. should only be used when citing a source with three or more authors; exact rules will vary between style guides.
  • Any changes associated with the four points above can be made directly to the text, no comment required (unless the customer has inexplicably italicized et al. throughout, in which case you might want to briefly explain why you have or have not made changes to their approach).

Using et. al in In-Text Citations

How many authors need to be involved before et al. comes into play? Most styles require it for three or more authors, but there can be variations.

The table below shows how many authors are needed for et al. to be required in citations written in various common referencing styles. Note that the styles may have additional rules for avoiding ambiguity, for example.

Referencing style Rules
APA 7th ed Three or more authors (note that APA 6th ed has different rules)
Harvard Three or more authors (note: Harvard rules can vary between institutions).
MLA 9th ed Three or more authors.
CMoS 17th ed Four or more authors.
IEEE Three or more authors (note that IEEE italicizes et al.).
OSCOLA Four or more. But... OSCOLA uses "and others," not "et al."

Et al. in References

Many reference systems have different rules for how et al. is used in the reference list compared to how it is used in in-text citations or footnotes.

Of the six referencing systems discussed here, the awkward ones are:

  • APA 7th ed: Include up to 20 authors in the reference. For 21 or more authors, include the first 19, an ellipsis, and the final name.
  • Harvard: The general rule is to include all authors in a reference list or bibliography, but if this starts to get ridiculous, then leave a comment advising the customer to check with their institution (remembering that Harvard guidelines can vary).
  • CMoS 17th ed: Include up to 10 authors in a bibliography entry, followed by et al.
  • IEEE: Include up to six authors in a reference, followed by et al.


As a proofreader, you’re going to encounter “et al.” at some point. You don’t need to memorise everything in this short guide; the main thing is to be aware of the issues and know when they’re likely to be affected by a referencing style.

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