How to Use 'Et Al.' in Academic Writing: APA, MLA, and Chicago Rules Explained

If you've ever been unsure whether to write all the authors' names or just the first one followed by "et al.," you're not alone. Knowing how to use et al. in citations correctly is one of those details that trips up even experienced academic writers, because the rules differ between citation styles and have changed between editions of the major style guides. This article explains exactly what et al. means, when to use it, and how the rules differ across APA, MLA, and Chicago, with examples for each.

What Does Et Al. Mean?

Et al. is a Latin abbreviation for "et alii," meaning "and others." It's used in academic citations to indicate that a source has multiple authors beyond those specifically named. The abbreviation allows writers to acknowledge all contributors to a work without listing every name in full each time the source is cited.

A few points of punctuation to note before going further. "Et" is a complete Latin word meaning "and" and is never followed by a period. "Al." is an abbreviation of "alii" and always takes a period. So the correct form is always "et al." with a period after "al" and never "et. al." or "et al" without the period. In many modern style guides, et al. is no longer italicized, though you may still see it italicized in older publications.

Et Al. in APA Style (7th Edition)

APA 7th edition simplified the et al. rules significantly compared to the 6th edition. The current rules are straightforward:

• One or two authors. Always list all authors in every citation. Never use et al. for works with one or two authors.
• Three or more authors. Use et al. from the first citation onward. You do not need to list all authors the first time, as was required in APA 6th edition.

In text citation examples:

• One author: (Smith, 2022)
• Two authors: (Smith and Jones, 2022)
• Three or more authors: (Smith et al., 2022)

Note that in APA in text citations, the ampersand (&) is used between author names inside parentheses, but "and" is spelled out when the citation appears as part of a sentence. For example: "Smith and Jones (2022) found that..." versus "...as previous research has shown (Smith & Jones, 2022)."

In the APA reference list, all authors are listed regardless of how many there are, up to 20. For works with 21 or more authors, list the first 19 authors, followed by an ellipsis, and then the final author's name.

What If Two Citations Shorten to the Same Et Al. Form?

If two different sources by different author groups would both shorten to the same et al. form in the same year, APA requires you to include enough additional author names to distinguish the two citations. For example, if Smith, Jones, Brown, and Wilson (2022) and Smith, Jones, Taylor, and Lee (2022) would both shorten to "Smith et al. (2022)," you would write "Smith, Jones, Brown, et al. (2022)" and "Smith, Jones, Taylor, et al. (2022)" to distinguish them.

Et Al. in MLA Style (9th Edition)

MLA style uses et al. differently from APA. The current rules under MLA 9th edition are:

• One or two authors. List all authors in the Works Cited entry and in in text citations.
• Three or more authors. In the Works Cited entry, list the first author followed by et al. In text citations follow the same pattern.

In text citation examples:

• Two authors: (Smith and Jones 45)
• Three or more authors: (Smith et al. 45)

Works Cited entry format for three or more authors:

Smith, Jane, et al. Title of the Work. Publisher, 2022.

Note that in MLA in text citations, there is no comma between the author name and the page number, unlike APA which uses a comma between author and year. MLA does not include the year in in text citations.

Et Al. in Chicago Style

Chicago style has two documentation systems: notes and bibliography (used in humanities) and author date (used in social sciences). The et al. rules differ slightly between them.

Chicago Notes and Bibliography

• Up to three authors. List all authors in footnotes and bibliography entries.
• Four or more authors. In footnotes, list the first author followed by et al. In the bibliography, you may either list all authors or use et al. after the first author. Most style guides recommend listing all authors in the bibliography for complete attribution.

Footnote example with four or more authors:

Jane Smith et al., Title of the Work (Publisher, 2022), 45.

Chicago Author Date

• Up to three authors. List all authors in in text citations and reference list entries.
• Four or more authors. In in text citations, list the first author followed by et al. and the year. In the reference list, list all authors.

In text citation example with four or more authors:

(Smith et al. 2022)

Et Al. Rules at a Glance

Common Et Al. Mistakes to Avoid

• Writing "et. al." with a period after "et." "Et" is a complete word, not an abbreviation. The period goes after "al." only. The correct form is always "et al." never "et. al."
• Writing "et al" without a period. "Al." is always abbreviated with a period. Omitting it is a common proofreading miss.
• Using et al. for two author works. Both APA and MLA require all author names when there are only two authors. Et al. is only appropriate for three or more authors in APA and MLA, and four or more in Chicago.
• Applying APA 6th edition rules to a 7th edition paper. APA 6th edition required listing all authors up to five on first citation and then using et al. from the second citation. APA 7th edition simplified this: use et al. from the first citation for any work with three or more authors. If you learned APA citations before 2020, double check you're applying the current rules.
• Using et al. in the reference list in APA. In APA, et al. is only for in text citations. The reference list must include all author names up to 20, regardless of how many authors the work has.
• Italicizing et al. unnecessarily. Current editions of APA, MLA, and Chicago do not require et al. to be italicized. You may see it italicized in older publications, but in current academic writing it's treated as a standard English abbreviation.

Et Al. in Different Contexts

Et al. in a sentence (narrative citation)

When et al. appears as part of a sentence rather than inside parentheses, it works the same way grammatically. The sentence reads naturally with et al. in place of the additional author names:

Correct: Smith et al. (2022) found that participants who received the intervention showed significant improvement.

The period after "al." is part of the abbreviation, not the end of the sentence. If the sentence ends with et al., you don't add a second period. The abbreviation period serves as the sentence period.

Et al. for corporate or institutional authors

Et al. is used for human authors only. If a source is authored by a government body, organization, or institution, spell out the full name rather than abbreviating with et al., even if the institutional name is long. Use abbreviations for institutional authors according to the rules of your specific style guide.

Et al. in a bibliography or reference list

Whether et al. appears in a reference list entry depends on the style guide. In APA, it never appears in the reference list. In MLA, it does appear in Works Cited entries for sources with three or more authors. In Chicago, practice varies by system and by the number of authors. Always check the specific rules for your required style guide before finalizing your reference list.

FAQs

When should I use et al. in APA citations?

In APA 7th edition, use et al. in in text citations whenever a source has three or more authors. Use it from the first citation onward. In the reference list, always list all authors up to 20 regardless of how many there are. If a work has 21 or more authors, list the first 19, add an ellipsis, and then list the final author's name.

Is there a period after et al.?

Yes. The period goes after "al." because it is an abbreviation of the Latin word "alii." The correct form is "et al." with a period. "Et" is a complete word and does not take a period. Never write "et. al." and never omit the period after "al."

Does et al. need to be italicized?

No, not in current style guides. APA 7th edition, MLA 9th edition, and current Chicago style all treat et al. as a standard English abbreviation that does not require italics. You may see it italicized in older publications, but it's not required or recommended in current academic writing.

What is the difference between et al. rules in APA and MLA?

Both APA 7th and MLA 9th use et al. for sources with three or more authors in in text citations. The key differences are in format: APA includes the year in the citation (Smith et al., 2022) while MLA includes the page number (Smith et al. 45). APA uses a comma before the year; MLA uses no comma before the page number. In the reference list, APA lists all authors while MLA uses et al. after the first author for sources with three or more authors.

What happens if two sources shorten to the same et al. citation?

If two sources would produce identical et al. citations in the same year, you need to add enough additional author names to distinguish them. In APA, add author names after the first until the citations are distinguishable, then add et al. In MLA, the same principle applies. Always check your style guide for the specific rule for disambiguating identical et al. citations.

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