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CHICAGO 18TH EDITION GUIDE
Chicago Author-Date: 18th Edition Citation Guide
Chicago Author-Date cites sources with the author’s name and publication year in the text, usually in parentheses, and gives the full source details in an alphabetical reference list. A specific page or other locator can be added when you need to identify the exact part of a source.
Written and reviewed by Muzammal Amin · Checked against Chicago 18th-edition guidance
SHORT ANSWER
The basic pattern is: In-text citation: (Author Year, page) Reference-list entry: Author. Year. Full source details. For example: In-text citation (Yu 2020, 45) Reference-list entry Yu, Charles. 2020. Interior Chinatown. Pantheon Books. Need the citation rather than the rules? Use the Chicago Citation Generator and select Author-Date to generate the in-text citation and reference-list entry from the same reviewed source.
ON THIS PAGE
- What is Chicago Author-Date?
- What is the basic Chicago Author-Date citation format?
- When should I include a page number?
- What locators can Chicago Author-Date use besides page numbers?
- How do Chicago Author-Date citations work with one author?
- How do Chicago Author-Date citations work with two authors?
- How do Chicago Author-Date citations work with three or more authors?
What is Chicago Author-Date?
Author-Date is one of the two citation systems used in Chicago style.
It has two essential parts:
- a brief text citation that identifies the author and year, with a locator when needed;
- a corresponding reference-list entry containing the full publication details.
The system is widely used in the sciences and social sciences, although the required style ultimately depends on your instructor, department, journal, or publisher.
Chicago’s other system is Notes & Bibliography, which uses numbered footnotes or endnotes instead of ordinary parenthetical author-year citations.
If your assignment asks for footnotes, shortened notes, or a bibliography rather than parenthetical citations, use the Chicago Notes & Bibliography guide.
What is the basic Chicago Author-Date citation format?
The most common parenthetical pattern is:
(Author Year, locator)
For example:
(Yu 2020, 45)
There is no comma between the author and year. A comma separates the year from a page number or another locator.
If you are citing the source generally rather than a specific passage, the locator can be omitted:
(Yu 2020)
The corresponding reference-list entry places the year immediately after the author:
Yu, Charles. 2020. Interior Chinatown. Pantheon Books.
When should I include a page number?
Include a page number or another locator when it helps the reader find the specific material you are citing, especially for a quotation or a precise passage.
For example:
(Yu 2020, 45)
If you are referring to the source as a whole, a locator may not be necessary:
(Yu 2020)
The locator belongs to the individual citation, not automatically to the permanent source record.
That means the same book can be cited at several different places:
(Yu 2020, 45)
(Yu 2020, 48)
without creating multiple book entries in the reference list.
The Chicago Citation Generator keeps citation-specific locators separate from the underlying source details for this reason.
What locators can Chicago Author-Date use besides page numbers?
Pages are common, but they are not the only way to identify a location.
Depending on the source, a citation may use:
- page;
- page range;
- chapter;
- section;
- paragraph;
- volume;
- figure;
- line;
- document number;
- timestamp.
For an ebook without fixed page numbers, for example, Chicago’s official examples show that a chapter can be used:
(Roy 2008, chap. 6)
A constitutional document in an electronic collection may use more than one locator:
(Kurland and Lerner 1987, chap. 10, doc. 19)
For a video, a timestamp can identify the relevant portion.
Use a locator that genuinely helps the reader find the cited material. Do not invent paragraph numbers for a webpage that does not actually number its paragraphs.
How do Chicago Author-Date citations work with one author?
For one author, use the surname and year.
In-text citation
(Yu 2020, 45)
Reference list
Yu, Charles. 2020. Interior Chinatown. Pantheon Books.
The full first name belongs in the reference list when available, while the parenthetical citation normally uses only the surname.
How do Chicago Author-Date citations work with two authors?
For two authors, list both surnames in the text.
In-text citation
(Binder and Kidder 2022, 117–18)
Reference list
Binder, Amy J., and Jeffrey L. Kidder. 2022. The Channels of Student Activism: How the Left and Right Are Winning (and Losing) in Campus Politics Today. University of Chicago Press.
Chicago 18 lists both authors in the text when there are exactly two.
How do Chicago Author-Date citations work with three or more authors?
Chicago 18 changed the author threshold for text citations.
For three or more authors, use the first author’s surname followed by et al. in the text.
For example:
(Booth et al. 2016, 51)
In the reference list:
- list all authors when there are up to six;
- for more than six authors, list the first three followed by et al.
| Number of authors | Author-Date text citation | Reference list |
|---|---|---|
| 1 | List author | List author |
| 2 | List both | List both |
| 3–6 | First author + et al. | List all |
| 7+ | First author + et al. | First 3 + et al. |
This is an important Chicago 18th-edition rule. Older Chicago 17 guides may show different thresholds.
See Chicago 18th Edition for the other major citation changes.
How does a Chicago Author-Date reference list work?
The reference list contains the full source information corresponding to the citations in the text.
Entries are normally arranged alphabetically by the first author’s surname or the appropriate element used in place of an author.
A key feature of Author-Date style is that the publication year appears immediately after the author.
Notes & Bibliography bibliography
Yu, Charles. Interior Chinatown. Pantheon Books, 2020.
Author-Date reference list
Yu, Charles. 2020. Interior Chinatown. Pantheon Books.
The two entries describe the same book, but the position of the date reflects the different citation systems.
Do not copy a Notes & Bibliography entry into an Author-Date reference list without reformatting it.
Is a Chicago reference list the same as a bibliography?
No.
A reference list belongs to Author-Date and is designed to work with author-year citations in the text.
A bibliography normally belongs to Notes & Bibliography and works with numbered notes.
Both lists commonly arrange sources alphabetically, but their entry structure differs.
If your assignment specifically asks for a Chicago bibliography, see the Chicago Bibliography guide.
How do narrative citations work in Chicago Author-Date?
You do not always need to put both the author and year inside one set of parentheses.
If the author is part of your sentence, the year can follow the name.
For example:
Ivy Smith (2024) argues that …
This construction refers directly to Smith as the author.
By contrast:
The same pattern has been documented elsewhere (Smith 2024).
uses a parenthetical citation to refer to the work.
The distinction can matter stylistically: Author (Year) names the person in the sentence, while (Author Year) functions as the compact citation to the work.
Use whichever construction makes the sentence clearer.
How do I cite several sources in one Chicago Author-Date citation?
When several sources support the same statement and are placed together inside one parenthetical citation, Chicago separates them with semicolons.
For example:
(Chan 1991; Lee 2003; Kurashige 2016)
Do not join separate author-date references with ordinary commas in a way that makes it unclear where one source ends and another begins.
If different sources support different parts of the same sentence, make sure the placement of each citation clearly identifies what it supports. Sometimes rewriting the sentence is clearer than attaching multiple ambiguous citations at the end.
What if the author is an organization?
An organization can serve as the author when no individual author is responsible for the work or when the organization is the appropriate credited creator.
Chicago’s official webpage examples include citations such as:
(Google 2023)
and reference-list entries beginning with the organization name.
For long organization names that will appear repeatedly, Chicago also provides guidance for using a recognizable abbreviation in author-date citations when appropriate. The reference list should make the identity of the organization clear.
Do not automatically treat the website name as the author if an individual author is actually credited.
For webpage-specific cases, see the Chicago Website Citation guide.
What if a source has no publication date?
For an undated source that requires a formal Author-Date citation, Chicago uses n.d. for “no date.”
A formal reference-list entry for an undated webpage can include an access date.
For example, the official Chicago quick guide shows an undated Yale University webpage in the reference list as:
Yale University. n.d. “About Yale: Yale Facts.” Accessed March 8, 2022. https://www.yale.edu/about-yale/yale-facts.
The corresponding author-date citation follows the same no-date logic:
(Yale University n.d.)
An archived version may sometimes be cited instead of relying on the live page.
Do not use n.d. merely because you have not looked for the date. First check whether the page gives a publication, revision, effective, or last-modified date that is appropriate for the source.
What if the same author has more than one work from the same year?
When works would otherwise have identical author-year citations, Chicago can distinguish them by adding letters to the year:
2024a
2024b
The letters appear in both the text citation and the reference-list entry.
For example:
(Author 2024a)
(Author 2024b)
The reference list determines which work receives each letter according to Chicago’s ordering rules.
Chicago 18 also confirms that lettered years can be used to distinguish works with the same leading author information when the ordinary shortened author form would otherwise be ambiguous.
Do not assign a, b, and so on randomly before the reference list is organized.
What if two cited authors have the same surname?
Author-Date citations must remain unambiguous.
If two different authors share a surname and the citations could be confused, additional identifying information may be needed, such as an initial or, in unusual cases, a short title.
The goal is not to make every citation longer. Add only enough information to distinguish the works clearly.
How do books work in Chicago Author-Date?
For a modern book, the basic reference-list pattern is:
**Last Name, First Name. Year. Book Title. Publisher.**
Official-style example
Yu, Charles. 2020. Interior Chinatown. Pantheon Books.
In-text
(Yu 2020, 45)
Chicago 18 no longer normally requires a place of publication for modern books.
For editions, editors, translations, ebooks, multiple authors, and other variations, see the Chicago Book Citation guide.
How do journal articles work in Chicago Author-Date?
A journal article reference usually identifies:
- author;
- publication year;
- article title;
- journal title;
- volume;
- issue;
- full article page range or article identifier;
- DOI-based URL or other appropriate online location.
The reference-list entry includes the page range for the article as a whole when page numbers are available.
The in-text citation uses the specific page or pages you are citing.
Example
Reference list:
Dittmar, Emily L., and Douglas W. Schemske. 2023. “Temporal Variation in Selection Influences Microgeographic Local Adaptation.” American Naturalist 202 (4): 471–85. https://doi.org/10.1086/725865.
In-text:
(Dittmar and Schemske 2023, 480)
For DOI handling, volume and issue information, article IDs, multiple authors, and online articles, see Chicago Journal Article Citation.
How do book chapters work in Chicago Author-Date?
A chapter in an edited book is cited under the chapter author when that chapter is the work being referenced.
The reference-list entry identifies both:
- the chapter; and
- the edited book containing it.
Chicago 18 no longer requires the full chapter page range in a standard reference-list entry.
The specific page being cited still belongs in the in-text citation when applicable.
The official Chicago example follows this pattern:
Doyle, Kathleen. 2023. “The Queen Mary Psalter.” In The Book by Design: The Remarkable Story of the World’s Greatest Invention, edited by P. J. M. Marks and Stephen Parkin. University of Chicago Press.
In-text:
(Doyle 2023, 64)
See Chicago Book Chapter Citation for the complete structure and common variations.
How do webpages work in Chicago Author-Date?
A webpage may be cited formally when the source needs a reference-list entry.
Depending on what the page provides, the citation may use:
- individual author;
- organization as author;
- page title;
- site or section title;
- publication, revision, effective, or last-modified date;
- access date when no date is available;
- URL;
- archived URL where appropriate.
Chicago notes that some website content can simply be described in the text when a formal citation is unnecessary.
For a formal citation, make the reference-list entry match the author-year form used in the text.
See Chicago Website Citation for dated pages, undated pages, organization authors, access dates, and archived webpages.
Should I include a DOI or URL?
For journal articles consulted online, Chicago recommends including an appropriate online location in the reference-list entry. A DOI-based URL is preferred when one is available.
For example:
https://doi.org/10.1086/725865
A DOI is useful because it identifies the scholarly work independently of the particular database or webpage where you found it.
For books consulted online, Chicago may use a URL, database name, or ebook format depending on how the source was accessed.
For ordinary webpages, use the relevant page URL.
Do not add a DOI or URL to the parenthetical Author-Date citation itself. It belongs in the reference-list entry.
What changed in Chicago 18 for Author-Date?
Several 18th-edition changes directly affect Author-Date users.
Author thresholds changed
In a text citation:
- list one author;
- list both authors for a two-author work;
- for three or more authors, use the first author followed by et al.
In a reference list:
- list up to six authors;
- for more than six, list the first three followed by et al.
Modern books usually omit place of publication
A city is no longer normally required before the publisher in modern book citations.
Chapter page ranges are no longer required in reference lists
A chapter’s full page range can be omitted from the standard reference entry. Cite the specific page in the text when needed.
Journal month or season can usually be omitted
Chicago 18 allows a month or season to be omitted in most journal citations.
Repeated author names are written again
Chicago now prefers repeating the author’s name in reference-list entries instead of replacing it with a 3-em dash.
These differences matter when you are copying examples from older handouts or citation generators.
Read Chicago 18th Edition: What Changed for the broader update.
Chicago Author-Date vs Notes & Bibliography
Both are Chicago systems, but they should not be mixed casually.
| Feature | Author-Date | Notes & Bibliography |
|---|---|---|
| Main text citation | (Author Year, page) | Superscript note number |
| Detailed source citation | Reference list | Footnote/endnote |
| Repeated citation | Repeat author-year form | Usually shortened note |
| Final source list | Reference list | Usually bibliography |
| Year in final entry | Immediately after author | Usually later in entry |
| Common use | Sciences/social sciences | Humanities |
If you need numbered notes rather than parenthetical citations, switch to the Chicago Notes & Bibliography guide.
For a broad overview of both systems, see the Chicago Style Guide.
What are common Chicago Author-Date mistakes?
Adding a comma between the author and year
Incorrect:
(Yu, 2020, 45)
Chicago Author-Date normally uses:
(Yu 2020, 45)
Using the Notes & Bibliography form in a reference list
Author-Date puts the year immediately after the author.
Do not copy a bibliography entry from Notes & Bibliography without reformatting it.
Listing every author in a three-author text citation
Chicago 18 uses the first author + et al. for three or more authors in the text.
Leaving out the specific page for a quotation
If a source has stable page numbers and you are quoting or pointing to a precise passage, give the useful locator.
Putting a page number into the permanent book record
The page belongs to the citation occurrence when it identifies the passage being used. A later citation to the same book may need a different page.
Adding an access date to every webpage
Access dates are especially relevant when a webpage has no publication or revision date. Do not add one mechanically to every URL.
Treating n.d. as a substitute for checking the page
Use n.d. when the source truly does not provide an appropriate date, not simply because the date was missed during metadata import.
Using 17th-edition author thresholds
Chicago 18 changed how many authors are listed before et al. is used.
Trusting imported metadata without review
Automatically retrieved records can contain incomplete titles, incorrect author parsing, a different book edition, missing dates, or inconsistent journal fields.
Review the source information before submitting the citation.
How to generate a Chicago Author-Date citation
The Chicago Citation Generator can produce the in-text citation and reference-list entry from one reviewed source record.
1. Find the source
Search using a supported input such as:
- DOI;
- URL;
- ISBN;
- title or keywords;
- PMID or PubMed URL;
- BibTeX;
- RIS;
- supported PDF DOI detection;
- manual entry.
2. Review the metadata
Check:
- author names;
- title;
- publication year;
- publisher;
- journal;
- volume and issue;
- DOI;
- URL;
- ISBN;
- other relevant source fields.
3. Select Author-Date
The source can then be rendered as:
- In-Text Citation
- Reference List Entry
4. Add the cited location
Enter the page, chapter, section, paragraph, timestamp, or another useful locator for that citation occurrence.
5. Copy or save the citation
Copy the individual output or add the source to your reference list.
Switching from Author-Date to Notes & Bibliography does not require you to search for the source again.
For the technical workflow behind metadata lookup, normalization, CSL formatting, duplicate detection, and local source management, see How the Chicago Citation Generator Works.
Chicago Author-Date examples by source type
Use the dedicated source guides when you need the full metadata pattern and edge cases:
- Chicago Book Citation
- Chicago Journal Article Citation
- Chicago Website Citation
- Chicago Book Chapter Citation
For side-by-side examples showing the same source in both Chicago systems, browse Chicago Citation Examples.
Frequently asked questions
What is Chicago Author-Date?
Chicago Author-Date is a citation system that uses an author’s surname and publication year in the text and provides the full source details in an alphabetical reference list.
What does a Chicago Author-Date in-text citation look like?
A common citation looks like:
(Yu 2020, 45)
The author and year identify the source, while 45 identifies the page being cited.
Is there a comma between the author and year?
No. The standard form is (Author Year, page), not (Author, Year, page).
Do I always need a page number?
No. Use a locator when you need to identify a specific passage or location. A general reference to an entire work may use only the author and year.
How many authors are listed in a Chicago 18 Author-Date citation?
List both authors for a two-author work. For three or more authors, use the first author followed by et al. in the text.
How many authors go in the reference list?
List up to six authors. For more than six, list the first three followed by et al.
What if there is no publication date?
Use n.d. when a source truly provides no suitable publication or revision date. For an undated webpage, an access date is normally included in the formal reference entry.
Can an organization be the author?
Yes. An organization can serve as the author when it is the appropriate creator or responsible body for the source.
How do I cite more than one source in the same parentheses?
Separate the individual author-date references with semicolons, for example:
(Chan 1991; Lee 2003; Kurashige 2016)
What if the same author published two works in the same year?
Add letters to the year as needed, such as 2024a and 2024b, and use the same lettered dates in the text citations and reference list.
Does Chicago Author-Date use a bibliography?
Author-Date uses a reference list. A Chicago bibliography normally belongs to Notes & Bibliography.
Can Chicago Author-Date use footnotes?
Author-Date primarily uses text citations, but explanatory notes can still exist in a document. Do not convert ordinary author-date source citations into Notes & Bibliography-style footnotes unless the required publication style calls for that treatment.
Official Chicago sources
This guide was researched against current Chicago 18th-edition guidance, including:
- Chicago Author-Date: Sample Citations
- Chicago-Style Citation Quick Guide
- What’s New in the 18th Edition
- Chicago Style Q&A: Author-Date Locators
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