How to cite in Chicago author-date: formats, examples, and common mistakes

Chicago style contains two entirely different documentation systems, and picking the wrong one is the most common Chicago mistake of all. Notes-bibliography uses numbered footnotes or endnotes and is the default in history and much of the humanities. Author-date uses short in-text citations with a reference list and is the Chicago of choice in the sciences and social sciences. This guide covers the author-date system. If your department expects footnotes, you need the notes system and the free Chicago notes generator instead; the two systems format the same sources differently and must never be mixed in one document.

At a distance, Chicago author-date looks like APA: author and year in the text, alphabetised reference list at the end, one-to-one matching between the two. Up close, the punctuation is different in ways that markers spot immediately. Chicago puts no comma between author and year in the text, keeps headline-style capitalisation for every title, places the year immediately after the author in the reference list, and uses quotation marks around article titles where APA uses none.

This guide covers the in-text rules, reference list formats for journal articles, books, chapters, and websites, six worked examples, the five most common author-date mistakes, and how to generate the citations automatically.

Chicago author-date in-text citations: (Author Year, page)

The parenthetical form is the author's surname and the year with no comma between them: (Duarte 2022). A page reference follows the year after a comma, with no 'p.': (Duarte 2022, 215). The narrative form names the author in the sentence: Duarte (2022, 215) shows that cooperative irrigation schemes outlasted droughts that broke individual holdings.

Two and three authors are all named, with a serial comma in the three-author form: (Chen and Dubois 2021), (Chen, Dubois, and Ferro 2020). Four or more authors take et al.: (Osei et al. 2023). Multiple sources for one claim share one set of brackets, separated by semicolons: (Chen and Dubois 2021; Duarte 2022).

Two works by the same author in the same year take letter suffixes assigned by reference-list order, (Duarte 2022a, 2022b), and a source with no date is cited with n.d. in place of the year: (Meridian Academic n.d.).

Chicago also lets you point below the page level when it helps: (Grandin 2019, chap. 3) for a whole chapter, (Duarte 2022, fig. 2) for a figure, (Chen and Dubois 2021, table 4) for a table. Use these sparingly, and place every citation before the punctuation that closes the clause it supports, not floating after the full stop.

Author-date vs notes-bibliography: confirm you are in the right system

Before formatting a single entry, confirm which Chicago your department wants, because the two systems are not interchangeable and converting between them late is tedious. Some departments allow either system but require you to declare one, and the declaration then binds every chapter, including the ones you drafted earlier. The quick diagnostic:

• Author-date: (Duarte 2022, 215) in the running text, and a reference list whose entries put the year immediately after the author.
• Notes-bibliography: superscript numbers in the text, footnotes or endnotes carrying the full citation, and a bibliography whose entries hold the year near the end.
• History and most humanities departments usually want notes; social science and science departments usually want author-date. Your handbook, not this heuristic, is the authority.
• Never mix the systems: footnoted citations for some sources and in-text citations for others in the same thesis fails on sight.

Chicago reference list format for a journal article

The template: Surname, First Name. Year. "Article Title in Headline Case." Journal Title volume (issue): page range, followed by the DOI. The year sits directly after the author, closed with a full stop. The article title takes quotation marks, the journal title takes italics, and a colon separates the issue from the page range.

Worked example 1: Duarte, Marisol. 2022. "Irrigation Cooperatives and Drought Adaptation in Smallholder Agriculture." Journal of Rural Political Economy 34 (2): 210-229. https://doi.org/10.1000/jrpe.2022.0210.

Worked example 2, two authors: Chen, Wei, and Amara Dubois. 2021. "Field Notes at Scale: Team Ethnography and Its Discontents." Ethnographic Methods 15 (4): 388-405. https://doi.org/10.1000/em.2021.0388. Only the first author's name is inverted; subsequent authors appear in normal order.

Chicago reference list format for a book or chapter

The book template: Surname, First Name. Year. Title of Book in Italics and Headline Case. Place of publication: Publisher. Chicago, unlike APA 7, still records the place of publication before the publisher.

Worked example 3: Grandin, Elena. 2019. The Measured Field: Quantification in Agrarian Studies. Chicago: Lakefront University Press.

The chapter template: Surname, First Name. Year. "Chapter Title." In Title of Book, edited by Editor Name, page range. Place: Publisher. Note the order: the chapter's page range comes after the editor and before the place and publisher, which is unlike every other major style and is therefore worth double-checking in every chapter entry you write.

Worked example 4: Dubois, Amara. 2020. "Consent in Longitudinal Fieldwork." In Ethics for Field Researchers, edited by Wei Chen, 45-63. London: Meridian Academic.

Chicago reference list format for a website

Web sources follow the same author, year, title pattern, with the site name in roman type and a revision or access date anchoring pages that can change: Surname, First Name. Year. "Title of Page." Site Name. Last modified date. URL. When the page has no publication date at all, use n.d. in the year position and give an access date instead. Treat organisational authorship as normal rather than exceptional here: standards bodies, government agencies, and university offices are the authors of most of the web sources a thesis cites.

Worked example 5: Osei, Kwame. 2024. "Preparing Your Committee Meeting." Graduate Research Notes. Last modified February 9, 2024. https://www.example.org/committee-meeting.

Worked example 6, undated page with an organisational author: Meridian Academic. n.d. "Author Guidelines." Accessed July 12, 2026. https://www.example.org/author-guidelines. In the text this is cited as (Meridian Academic n.d.).

Headline case, quotation marks, and italics in Chicago

Chicago capitalises every title headline-style: first word, last word, and all principal words in between. This applies to article titles, chapter titles, book titles, and journal titles alike, and it is the most visible difference from APA's sentence case. Quotation marks and italics divide by container: titles of smaller things inside larger things, articles and chapters, take quotation marks; titles of the larger things, journals and books, take italics.

The reference list is alphabetised by author surname, entries take a hanging indent, and multiple works by the same author are ordered by year. Same-author, same-year entries carry the a, b, c suffixes your in-text citations depend on, so assign the letters in the list first and let the text follow.

Reports, theses, and grey literature in Chicago author-date

Most social-science theses cite more than journals and books, and the author-date pattern extends naturally. For a report, the organisation is the author, the year follows as usual, the title takes italics if the report is a standalone document, and a report or working-paper number slots in after the title. A thesis or dissertation is treated like a book whose publisher is the university, with the document type noted after the title: PhD diss. or master's thesis, followed by the institution.

A working-paper pattern, with a fictional institute standing in for yours: Meridian Institute for Rural Studies. 2023. "Credit Access After Consolidation." Working Paper 41. London: Meridian Institute for Rural Studies. In the text: (Meridian Institute for Rural Studies 2023), which you may abbreviate after a first flagged mention if the name is unwieldy. The habit to build is structural: identify the author, the year, the title, and the containing series, and the entry mostly writes itself.

The five most common Chicago author-date mistakes

These are the errors examiners flag most often in author-date manuscripts, and every one of them is checkable in a single pass through your reference list:

• Drafting in the wrong system. Footnoted citations in a thesis that specified author-date, or a mix of both systems, is the most damaging Chicago error because fixing it touches every page.
• APA punctuation imported. (Duarte, 2022) with a comma is APA; Chicago author-date is (Duarte 2022). One stray comma per citation, hundreds of citations.
• Sentence-case titles. Chicago keeps headline case for every title in the reference list. Titles pasted from databases in sentence case need re-casing.
• The year in the wrong place. In the reference list the year comes immediately after the authors, not at the end of the entry; year-at-the-end is notes-bibliography formatting.
• Page punctuation confusion. A comma introduces pages in the text, (Duarte 2022, 215), while a colon introduces the page range in a journal entry, 34 (2): 210-229. Swapping them is common and visible.

A pre-submission checklist for Chicago author-date

Chicago's failure modes are systematic rather than random: the same imported comma or misplaced year repeats through the whole list. So check one rule at a time across every entry, rather than one entry at a time against all the rules:

• No comma between author and year in any in-text citation.
• Year immediately after the author in every reference entry.
• Headline case on every title; quotation marks for articles and chapters, italics for journals and books.
• Colon before journal page ranges in the list; comma before page numbers in the text.
• Place of publication present for books; DOI present for every article that has one.
• Letter suffixes (2022a, 2022b) aligned between text and list, and undated sources carrying n.d. plus an access date.

Generate Chicago author-date citations automatically

Chicago's punctuation is fiddly enough that hand-formatting a long reference list reliably is a poor use of a research degree. For a one-off entry, the free Chicago author-date generator formats the reference from the details you supply. For the thesis itself, the Reference Manager renders your bibliography in Chicago author-date or any of 11 other styles from the same stored sources, so entries stay internally consistent and a style switch is a re-render.

The deeper protection is that CiteDash citations are database objects that resolve to real papers, never free-typed strings, so a citation cannot silently point at nothing. Claims drafted with AI are verified against held full-text PDFs by the Fact Checker before you see them, and retracted papers are badged and blocked from citation. Format gets you past the copy-editor; grounding gets you past the examiner.