In APA 7, use et al. for works with 3 or more authors starting from the very first citation — list only the first author's last name followed by "et al." In MLA 9, use et al. for works with 3 or more authors in both in-text citations and the Works Cited entry. In Chicago, use et al. in-text for 4 or more authors; list all authors in the bibliography unless there are 10 or more.
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Et al. is an abbreviation of the Latin "et alia" meaning "and others." The period at the end of "al" is not optional — it is an abbreviation, so "et al" (no period) is always wrong. Italicize or not? Neither APA 7 nor MLA 9 italicizes et al.; leave it in roman type.
APA 7 rule: 3+ authors, always et al.
APA 7 simplified the old rule. The old APA 6 rule said list all authors the first time for 3 to 5 authors, then shorten. APA 7 scrapped that. Now:
- 1 author: (Walker, 2017)
- 2 authors: (Walker & Harris, 2020) — always list both, every time
- 3+ authors: (Walker et al., 2021) — from the first citation onward
Example, 3-author source first citation in APA 7: "Sleep deprivation impairs consolidation (Walker et al., 2021)." No need to list all authors on the first mention.
The one exception in APA 7: if et al. would make two different sources ambiguous (e.g., Walker, Chen, & Park 2021 and Walker, Chen, & Torres 2021 would both be "Walker et al., 2021"), list enough additional authors to distinguish: (Walker, Chen, Park, et al., 2021) and (Walker, Chen, Torres, et al., 2021).
MLA 9 rule: 3+ authors use et al.
MLA 9 matches the "3 or more" threshold but applies it to both in-text and Works Cited.
- 1 author: (Walker 107)
- 2 authors: (Walker and Harris 220) — list both, joined by "and"
- 3+ authors: (Walker et al. 15) — first author's last name + et al.
Works Cited in MLA 9:
- 2 authors: Walker, Matthew, and Sarah Harris.
- 3+ authors: Walker, Matthew, et al.
This is a change from older MLA versions that used a different cutoff. MLA 9 is consistent: 3+ gets et al. everywhere.
Chicago rule: 4+ authors in-text, all authors in bibliography
Chicago (notes-bibliography) sets the in-text threshold higher.
- In-text (footnote shortened form): et al. for 4 or more authors.
- Bibliography: list all authors up to 10. If 11 or more, list the first 7 followed by et al.
First footnote for 4-author work: 1. Matthew Walker et al., Sleep and Memory (New York: Scribner, 2021), 107.
Bibliography entry, same 4-author work: Walker, Matthew, Sarah Harris, James Park, and David Chen. Sleep and Memory. New York: Scribner, 2021.
The Chicago threshold is different from APA and MLA. Check the style required before applying the rule.
Quick reference across styles
| Style | In-text threshold | Bibliography/Works Cited threshold | | --- | --- | --- | | APA 7 | 3+ authors use et al. (from first cite) | List up to 20 authors; then first 19, ellipsis, last author | | MLA 9 | 3+ authors use et al. | 3+ authors use et al. | | Chicago (NB) | 4+ authors use et al. | List all up to 10; 11+ list 7 then et al. | | Harvard | 3+ authors use et al. (varies) | Institution-specific; check rubric |
Examples side by side
Same 3-author source (Chen, Park, and Walker) cited across styles:
- APA 7 in-text: (Chen et al., 2022)
- MLA 9 in-text: (Chen et al. 15)
- Chicago in-text (footnote short form): Chen, Park, and Walker, Memory Study, 15. (All three listed because below the 4-author threshold.)
Same 5-author source (Chen, Park, Walker, Harris, and Torres):
- APA 7 in-text: (Chen et al., 2022)
- MLA 9 in-text: (Chen et al. 15)
- Chicago in-text: Chen et al., Memory Study, 15. (Threshold of 4+ triggers et al.)
Formatting details
- "et al." is not italicized in APA 7, MLA 9, or Chicago. Leave it in roman type.
- The period after "al" is required.
- There is no comma between the first author's last name and et al. in MLA ("Walker et al."). APA does use a comma before the year ("Walker et al., 2021").
- Never use "et al." in a sentence unless you are literally writing the citation ("Smith et al. found..."). In narrative prose, write out "Smith and colleagues" or "Smith and coauthors."
Common mistakes
- Writing "et. al." (period after "et") — wrong; "et" is not an abbreviation.
- Writing "et al" without the period — wrong.
- Italicizing "et al." — wrong in APA and MLA.
- Using et al. for 2-author sources — never acceptable in any style.
- Using et al. in APA 7 narrative: "Walker et al. (2021) found..." is correct; "Walker and colleagues (2021)" is also acceptable.
For the broader question of how to cite a source you are using more than once, see cite the same source multiple times. If your source uses direct quotes, you also need page numbers — see page numbers in citations.
For the full formatting rulebook, see our research paper guide. When you want a citation workflow that handles author thresholds automatically, start on our citation page.
Frequently asked questions
Is it "et al" or "et al."?
Always "et al." with the period. "Et" is a complete Latin word (meaning "and"); "al." is an abbreviation of "alia," which is why it needs the period.
Should et al. be italicized?
No. APA 7 and MLA 9 both leave et al. in roman (non-italic) type. Older style manuals used to italicize Latin abbreviations, but current conventions do not.
What about Harvard style?
Harvard varies by institution but typically matches APA: 3+ authors use et al. from the first citation. Always check your course rubric.
Can I use et al. for the first author plus "and others" in English?
In narrative prose, yes: write "Walker and colleagues" or "Walker and coauthors" for readability. In parenthetical citations, stick to et al.