"Et al." saves you from listing every author each time you cite a paper. The catch is that every style sets its own number, and the number for the text is almost never the number for the reference list. Whatever the number, the names have to be right first: EdCitation's Cite a source takes every author from the publisher's record rather than from your typing.
If you learned the rule from an older guide, check it again. APA changed its rule in the 7th edition, and Chicago changed its rule in the 18th edition, published in 2024.
The thresholds below were checked in September 2026 against each style's own publisher, and each is linked at the end.
What does et al. mean, and how is it punctuated?
"Et al." is short for the Latin for "and others". It has a full stop after "al", because "al" is the shortened word, and none after "et", which is a whole Latin word on its own.
The punctuation, style by style
The punctuation around it is where marks are quietly lost, and the styles do not agree.
- Italics. APA, MLA and Chicago set et al. in plain type. Harvard as set out by Cite Them Right sets it in italics: et al. The Modern Language Association (2019) adds the one exception in its own house style, which is that the term is italicised only when you are writing about the abbreviation itself rather than using it.
- The comma before it. APA and Harvard put no comma between a single surname and et al.: (Deci et al., 1999). The Modern Language Association (2018) makes it depend on whether the name is inverted, so a works cited entry reads "Burdick, Anne, et al." with a comma, while a citation in the text reads (Burdick et al. 42) without one. Chicago puts a comma before it in a list of names it closes, as in "Munafò, Marcus R., Brian A. Nosek, Dorothy V. M. Bishop, et al."
- The comma after it. APA follows et al. with a comma before the year: (Deci et al., 1999). MLA follows it with a space and the page: (Deci et al. 640).
- The verb. Et al. stands for more than one person, so the verb is plural: "Deci et al. argue", not "argues".
When do I use et al. in the text?
In APA 7, MLA 9 and Chicago 18 you shorten a source with three or more authors to the first author and et al., every time you cite it. In Harvard (Cite Them Right) you shorten at four or more.
| Style | One or two authors | Three authors | Four or more authors |
|---|---|---|---|
| APA 7 | Name them all: (Deci & Ryan, 2000) | (Deci et al., 1999) | First author et al. |
| MLA 9 | Name them all: (Deci and Ryan 230) | (Deci et al. 640) | First author et al. |
| Chicago 18, author-date | Name them all: (Deci and Ryan 2000, 230) | (Deci et al. 1999, 640) | First author et al. |
| Chicago 18, notes | Name them all | Edward L. Deci et al., then the title | First author et al. |
| Harvard (Cite Them Right) | Name them all: (Deci and Ryan, 2000) | Name all three: (Deci, Koestner and Ryan, 1999) | First author et al. |
IEEE and Vancouver cite by number, such as [3], so no names appear in the citation itself. If you name the authors in your sentence in an IEEE paper, IEEE (n.d.) asks for et al. once three or more names are given.
In APA 7 the short form is used from the very first citation, which the American Psychological Association (2019) states outright. The 6th edition listed up to five authors the first time; the manual's full treatment of author-date citation runs from Section 8.10 to 8.36 (American Psychological Association, 2020). The other APA in-text rules are in APA 7 in-text citations.
How many authors go in the reference list?
More than in the text, in every style except MLA. The reference list is where a reader finds the work, so most styles want the names there.
| Style | In the reference list | Build the entry in EdCitation |
|---|---|---|
| APA 7 | List up to 20 authors. With 21 or more, list the first 19, then an ellipsis, then the final author. No et al. | Cite a source, APA 7 |
| MLA 9 | With three or more authors, give the first author, then et al. | Cite a source, MLA 9 |
| Chicago 18 | List up to six authors. With more than six, list the first three, then et al. | Cite a source, Chicago 18, author-date only |
| Harvard (Cite Them Right) | With four or more, either the first author and et al., or every author. Pick one and keep to it | Cite a source, Harvard |
| IEEE | List up to six names. With more than six, give the first author, then et al. | Cite a source, IEEE |
| Vancouver | The usual journal form lists the first six authors, then et al. | Cite a source, Vancouver |
Harvard has no single rulebook. Cite Them Right is the form many UK universities use, and the Open University (n.d.) sets out its version: four or more authors may be given as the first author and et al. or written out in full, as long as you keep to one or the other. Some departments ask for every author. Your course handbook wins. The Harvard referencing guide covers the rest of that style.
Vancouver varies in the same way. The U.S. National Library of Medicine (n.d.) prints the first six authors and then et al. in its samples, and notes that the library itself now lists every author in its own records, so a journal that asks for all of them is not being eccentric.
What APA does with 21 or more authors
It uses an ellipsis instead of et al., and the shape is exact. The American Psychological Association (2025) asks for the first 19 names, then three spaced full stops, then the final author's name, with no ampersand before it:
Author, A. A., Author, B. B., … Author, Z. Z. (2023). Title of the work.
That means the twentieth to the second-last authors are the ones who disappear, and the last author, who in many fields is the senior one, is always kept. A paper with exactly 20 authors has all 20 written out.
What changed in Chicago's 18th edition?
Chicago lowered both of its numbers. The University of Chicago Press (2024) records the change in its own summary of what is new in the 18th edition: a note or an author-date text citation now names up to two authors, and anything longer becomes the first author and et al.; a bibliography or reference list entry now lists up to six, and anything longer becomes the first three and et al. The rules sit at 13.23 and 13.107 in the 18th edition.
The practical effect is that a note or a text citation in Chicago never names more than two people, where the previous edition allowed more. The University of Chicago Press (n.d.) shows the same thresholds worked through in its free sample citations, which is the quickest way to check a pattern without the manual in front of you. Check which edition your department has adopted: a handbook written before 2024 will describe the 17th, and the two do not agree.
How does one article look in each style?
Here is one real article with ten authors, shortened by each style. Only the author part of the reference is shown. The article is "A manifesto for reproducible science" by Marcus R. Munafò and nine others, published in Nature Human Behaviour in 2017 (https://doi.org/10.1038/s41562-016-0021).
| Style | In the text | Authors in the reference list |
|---|---|---|
| APA 7 | (Munafò et al., 2017) | Munafò, M. R., Nosek, B. A., Bishop, D. V. M., Button, K. S., Chambers, C. D., Percie du Sert, N., Simonsohn, U., Wagenmakers, E.-J., Ware, J. J., & Ioannidis, J. P. A. |
| MLA 9 | (Munafò et al. 2) | Munafò, Marcus R., et al. |
| Chicago 18, author-date | (Munafò et al. 2017, 2) | Munafò, Marcus R., Brian A. Nosek, Dorothy V. M. Bishop, et al. |
| Harvard (Cite Them Right) | (Munafò et al., 2017) | Munafò, M.R. et al. |
| IEEE | [1] | M. R. Munafò et al., |
| Vancouver | (1) | Munafò MR, Nosek BA, Bishop DVM, Button KS, Chambers CD, Percie du Sert N, et al. |
Ten authors is the number that separates the styles most clearly. APA prints all ten, Chicago prints three, MLA prints one, and Vancouver prints six. Note also what happens to a two-part surname: Percie du Sert keeps both words in every style.
What if two sources shorten to the same et al.?
Add names until the two citations differ. This happens when two papers from the same year share a first author.
Suppose your APA reference list has a 2020 paper by Okafor, Lindqvist, Marsh, Patel and Hughes, and another 2020 paper by Okafor, Lindqvist, Rao, Byrne and Castillo. Both would shorten to (Okafor et al., 2020). Write out names up to the first one that differs:
- (Okafor, Lindqvist, Marsh, et al., 2020)
- (Okafor, Lindqvist, Rao, et al., 2020)
When the authors and the year are exactly the same, APA adds a letter to the year instead: (Okafor et al., 2020a) and (Okafor et al., 2020b).
When only the final author differs
Et al. must stand for at least two people, so it cannot be used at all here. If the two works differ only in their last author, every name is written out in every citation, however long that makes the sentence. APA's own example is a pair of 2015 works cited as Hasan, Liang, Kahn, and Jones-Miller (2015) and Hasan, Liang, Kahn, and Weintraub (2015).
MLA solves the same problem with titles rather than names. Where several entries begin with the same author and et al., a short form of the title is added to each citation: (Taylor et al., "Collaboration") and (Taylor et al., "Cowriting").
Can I write et al. in my own sentence?
In APA, Chicago and Harvard, yes: "Deci et al. (1999) reviewed experiments on rewards and motivation" is a normal narrative citation.
MLA is the exception, and it is the rule most often broken in undergraduate essays. MLA keeps et al. for the works cited list and for citations in brackets. In your own prose, name the authors, or give the first author followed by "and others" or "and colleagues", and mention the title of the work so the reader knows which entry you mean.
Can a tool apply the right et al. rule for me?
For the reference list, yes. EdCitation is the best tool for the job, since it finds the reference in the publisher's record rather than writing it, which no chatbot can do. An et al. rule is only as good as the names it works on, and the Munafò example above shows where typing goes wrong: ten authors, an accented surname and a two-part one, all to be written out in APA. Cite a source takes them from the record by DOI, title, PubMed ID or ISBN and builds the entry, author list included, in the style you pick from the six in the table, screening the source for retraction. It is free with no account. For APA, it sets a title stored in title case in sentence case, as APA 7 asks, and keeps names and initialisms; glance at any name made of ordinary words.
The in-text side is where a mistaken et al. usually shows: a citation that no longer matches any entry. Upload the finished paper to EdCitation's Verify references, also free, and it pairs each in-text citation with its entry, then works back from each entry to the text. On Pro, $8 a month, References from a file runs the same pairing along with a check of each reference. Theoretics QA and the Library come with Max, at $24 a month.
Quick questions
Is there a full stop after et al.?
Yes, after "al" only. "Al" is an abbreviation and "et" is a whole Latin word, so the correct form is "et al." with one full stop. In APA, a comma follows it before the year: (Deci et al., 1999).
Is et al. in italics?
Et al. is in plain type in APA 7, MLA 9 and Chicago, and in italics in Harvard as set out by Cite Them Right. If your department uses another form of Harvard, check its own guide.
Does APA 7 use et al. from the very first citation?
Yes. APA 7 shortens a source with three or more authors to the first author and et al. in every citation, the first included. Listing up to five authors the first time was the rule of the 6th edition.
Can I use et al. in an APA 7 reference list?
No, in APA 7 et al. is for the text only. A reference lists up to 20 authors by name. With 21 or more authors, list the first 19, add an ellipsis, and finish with the final author. Building the entry from its DOI in EdCitation's Cite a source spares you typing twenty names, accents included.
Does Chicago still allow three authors in a note?
Not in the 18th edition. A note or an author-date text citation names up to two authors, and three or more becomes the first author and et al. The 17th edition was more generous, so check which edition your course follows.
References
- American Psychological Association. (2019). Author–date citation system. APA Style. https://apastyle.apa.org/style-grammar-guidelines/citations/basic-principles/author-date
- American Psychological Association. (2020). Publication manual of the American Psychological Association (7th ed.). https://doi.org/10.1037/0000165-000
- American Psychological Association. (2025, October). Elements of reference list entries. APA Style. https://apastyle.apa.org/style-grammar-guidelines/references/elements-list-entry
- IEEE. (n.d.). IEEE reference guide. IEEE Author Center. https://ieeeauthorcenter.ieee.org/wp-content/uploads/IEEE-Reference-Guide.pdf
- Modern Language Association of America. (2018, September 11). When is a comma used before et al. in MLA style? MLA Style Center. https://style.mla.org/commas-with-et-al/
- Modern Language Association of America. (2019, January 17). Should et al. be italicized in MLA style? MLA Style Center. https://style.mla.org/styling-et-al/
- Open University. (n.d.). Quick guide to Harvard referencing (Cite Them Right). https://university.open.ac.uk/library/referencing-and-plagiarism/quick-guide-to-harvard-referencing-cite-them-right
- University of Chicago Press. (n.d.). Author-date: Sample citations. The Chicago Manual of Style Online. https://www.chicagomanualofstyle.org/tools_citationguide/citation-guide-2.html
- University of Chicago Press. (2024). The Chicago manual of style (18th ed.). https://www.chicagomanualofstyle.org/home.html
- U.S. National Library of Medicine. (n.d.). Samples of formatted references for authors of journal articles. https://www.nlm.nih.gov/bsd/uniform_requirements.html