Every rule on one page
The first column is what appears in your sentences or footnotes. The second is the full entry at the end of the paper. Read them separately, because almost every style treats them differently.
| Style | In the text or notes | Reference list or bibliography |
|---|---|---|
| APA 7th | 3 or more authors: first author et al. from the first citation | Up to 20 authors listed; 21 or more: first 19, an ellipsis, then the last author |
| MLA 9th | 3 or more: first author et al. | 3 or more: first author, et al. |
| Chicago 18th | Notes and author-date text: up to 2 named; 3 or more: first author et al. | Up to 6 listed; 7 or more: first three, then et al. |
| Turabian 9th | Notes: up to 3 named; 4 or more: first author et al. | Up to 10 listed; 11 or more: first seven, then et al. |
| Harvard (Cite Them Right) | 4 or more: first author et al. | 4 or more: first author et al. is allowed; many universities ask for every name |
| IEEE | Numbered, [1]; names only if you write them into the sentence | Up to 6 listed; 7 or more: first author et al. |
| Vancouver | Numbered, (1) or superscript | More than 6: first six, then et al. |
| AMA 11th | Numbered, superscript | Up to 6 listed; 7 or more: first three, then et al. |
| Oxford (footnotes) | 4 or more: first author et al. | Varies by university; no single official manual |
| OSCOLA 5th | 4 or more: first author and others | 4 or more: first author and others, surname first |
The pattern is easier to remember as three families. The author-date styles, APA, MLA and Harvard, name authors in the sentence and shorten early so the text stays readable. The note styles, Chicago, Turabian, Oxford and OSCOLA, shorten inside the footnote but keep longer lists in the bibliography. The numbered styles, IEEE, Vancouver and AMA, never name authors in brackets at all, so their et al. rule lives only in the reference list.
What et al. means and how to write it
Et al. is short for the Latin et alii, and others. The details trip people up more than the rule itself, so here they are in one place.
| Question | Answer |
|---|---|
| Where does the full stop go? | After al only. Et is a whole word, al is the abbreviation: et al., never et. al. |
| Italics? | Not in APA, MLA or Chicago. IEEE references commonly italicise it. |
| Comma before it? | Yes in an MLA works cited entry and after a list of names in Chicago. No in an APA in-text citation, where the comma comes before the year |
| Singular or plural verb? | Plural, because it stands for several people: Chen et al. found, not Chen et al. finds |
| Does OSCOLA use it? | No. OSCOLA writes and others in English |
| Can it replace one name? | No. With two authors, every style names both |
One real paper, nine authors, ten styles
Rules are easier to trust when you can see them work. This is a real nine author article from our study of 1,000 Crossref records: Chen and colleagues in Analytical Chemistry, volume 96, issue 32, 2024. Nine authors is a useful number because it crosses almost every style's line, and it shows clearly where each one cuts.
Notice the spread. The same nine people appear as all nine names in APA and Turabian, as three names in Chicago 18 and AMA, as six in Vancouver, and as one name with et al. or and others everywhere else. If you switch a paper from one style to another, the author lists have to be rebuilt, not just repunctuated.
Et al. by the numbers
Single author papers are no longer the norm. In our random sample of 1,000 journal article records, 46 percent had three or more authors and 32.2 percent had four or more. For papers published since 2015 the share with three or more rose to 56.9 percent, against 29.1 percent before 2000. Ten percent had seven or more authors, the point where IEEE, AMA and Vancouver shorten the reference list, and 0.6 percent had 21 or more, the only case where APA shortens its reference list.
| Authors on the paper | All years | Since 2015 | Rule it triggers |
|---|---|---|---|
| 3 or more | 46.0% | 56.9% | Et al. in APA, MLA and Chicago text |
| 4 or more | 32.2% | 41.4% | Et al. in Harvard, Oxford and Turabian notes; and others in OSCOLA |
| 7 or more | 10.1% | 15.7% | Shortened lists in Chicago 18, IEEE, AMA and Vancouver |
| 11 or more | 2.4% | 4.2% | Shortened Turabian bibliography |
| 21 or more | 0.6% | 1.3% | APA's first 19, ellipsis, last author |
The cases that catch people out
Two different papers that shorten to the same thing.If Chen, Zhang and Xiao (2024) and Chen, Liu and Du (2024) both become Chen et al. (2024), a reader cannot tell them apart. APA's answer is to write out as many names as it takes to separate them before using et al., so the first becomes Chen, Zhang, et al. (2024) and the second Chen, Liu, et al. (2024).
The same authors twice in one year. When two works have identical author lists and the same year, APA adds a lower case letter to the year, 2024a and 2024b, in the text and in the reference list.
An organisation as author. A body such as the World Health Organization is one author, however many people worked on the report. It is never shortened to et al.
Initials only in the record.The full names in the Chicago and Turabian examples above come from a record that had them. Nearly one record in five gives first names as initials only, so for those styles check the article's byline before you trust the list.
Harvard and Oxford by university. Neither has one official manual. Cite Them Right, the most widely used Harvard guide in the UK, allows et al. for four or more authors in both places, but some universities require every name in the reference list, and Oxford footnote guides differ on the bibliography. Your course handbook outranks any general guide, including this one.
Frequently asked questions
How many authors before you use et al. in APA?
In the text, three. A work by three or more authors is cited with the first author's surname followed by et al. from the very first citation, as in (Chen et al., 2024). In the reference list APA works differently: you list every author up to 20, and for 21 or more you give the first 19, an ellipsis and then the final author.
Is et al. italicised?
Not in APA, MLA or Chicago, which treat it as an ordinary abbreviation in roman type. IEEE references commonly set it in italics. OSCOLA avoids the question by using the English words and others instead of the Latin.
Does et al. need a full stop?
Only after al, because al is short for alii while et is a complete Latin word meaning and. So it is always et al. with one full stop, never et. al. and never et al without the point in APA, MLA, Chicago or Harvard.
Do you put a comma before et al.?
It depends on the style and the position. MLA works cited entries do: Chen, Zhaoxin, et al. Chicago bibliographies do, because et al. follows a list of names. APA in-text citations do not put a comma before et al., only before the year: (Chen et al., 2024). Harvard in the Cite Them Right form writes Chen, Z. et al. without one.
Can I use et al. for two authors?
No. Every style on this page names both authors when there are two, in the text and in the reference list. Et al. only starts at three authors in APA, MLA and Chicago, and at four in Harvard, Oxford, OSCOLA and the Turabian notes.
What does OSCOLA use instead of et al.?
The words and others. When a work has more than three authors, OSCOLA gives the first author followed by and others, in footnotes and in the bibliography. The 5th edition kept this rule.
My instructor wants every author listed. Who wins?
Your instructor. Harvard in particular varies between universities: Cite Them Right allows the first author plus et al. in the reference list, but several universities ask for every name. Oxford referencing has no single official manual either. When a course guide sets its own rule, follow it consistently.
The bottom line
Count the authors, then check two numbers for your style: where it shortens the in-text citation and where it shortens the reference list. Three authors is the in-text line for APA, MLA and Chicago; four is the line for Harvard, Oxford, OSCOLA and the Turabian notes. In the list, APA keeps up to 20, Turabian up to ten, Chicago, IEEE and AMA up to six, Vancouver gives the first six and MLA shortens at three. With nearly half of journal articles now carrying three or more authors, this is a rule you will use in most of your citations, so it is worth getting right once.