Glossary

Using “et al.” correctly: the author threshold, the period, the plural verb

“Et al.” abbreviates the Latin et alii, meaning “and others.” It stands in for co-authors you have chosen not to name in an in-text citation once a source passes a set number of authors. The period belongs on “al.” only — “et” is a complete word, not an abbreviation.

Why it matters when you are writing

The threshold is style-specific, and getting it wrong is one of the most common formatting errors in a submitted manuscript. APA 7 uses “et al.” from the very first citation whenever a work has three or more authors. MLA 9 uses it for three or more. Chicago author–date names up to three and switches at four. Whichever applies, the reference list still spells out the authors in full, up to that style’s own cutoff.

The abbreviation is plural, so the verb agrees with it: “Okonkwo et al. argue,” not “argues.” It also belongs only in the citation, not in your prose — write “Okonkwo and colleagues found” if you want the names in the sentence itself. And it never appears in a two-author citation, where both names are always given.

One edge case is worth knowing before a reviewer finds it. If shortening two different sources produces the identical form — say two 2021 papers that both reduce to “Okonkwo et al., 2021” — APA asks you to name as many authors as it takes to tell them apart, then add “et al.” The point of the abbreviation is brevity, but never at the cost of ambiguity.

IN PRACTICE

A three-author source in APA 7

In text, first and every subsequent citation: (Okonkwo et al., 2021). In the reference list, all three authors appear in full: Okonkwo, A., Reyes, L., & Hardin, M.

OFTEN CONFUSED WITH

What Et al. is not

Etc.: “Etc.” stands for et cetera and refers to unnamed things; “et al.” refers to unnamed people, and the two are never interchangeable.
Et alia: Latin inflects for gender, but scholarly convention has settled on the single abbreviation “et al.” regardless of the authors’ genders.

Questions about et al.

How many authors before I can use “et al.”?

APA 7 and MLA 9: three or more, from the first citation. Chicago author–date: four or more. Vancouver-style numeric systems apply their own cutoff in the reference list itself.

Is it “et al.” or “et. al.”?

“Et al.” — one period, on “al.” only. “Et” is a full Latin word meaning “and,” so it takes no period of its own.

Should “et al.” be italicized?

No. It is naturalized into English and set in roman type in every major style, including in reference lists.

Does the reference list use “et al.” too?

Only past that style’s own limit. APA 7 lists up to 20 authors in full before truncating; MLA truncates at three. The in-text threshold and the reference-list threshold are separate numbers.

Related terms

In-text citation

Every borrowed idea in a paper carries an in-text citation: a brief marker — usually an author name plus a year, page, or number — that points to the full entry in your reference list.

Citation style

Every citation style — APA, MLA, Chicago, IEEE, Vancouver, Harvard — is a published rulebook governing how you signal a source in the text and format it in the reference list: punctuation, author order, italics, date placement.

Ibid.

Short for the Latin ibidem, “in the same place,” ibid.

Works Cited

MLA calls its end-of-paper source list the Works Cited page, and it holds only the sources you actually cited.

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