Chicago Style Citation: Notes-Bibliography and Author-Date

What Chicago style citation is

Chicago style comes from The Chicago Manual of Style, published by the University of Chicago Press and used widely by book publishers, historians and humanities departments. This guide follows its 17th edition, published in 2017. An 18th edition appeared in 2024 and adjusts a number of details, so if your syllabus names an edition, follow that one. Turabian, a student adaptation of Chicago, uses the same citation patterns.

What sets Chicago apart from APA and MLA is that it offers two complete systems. Both record the same facts — who wrote the source, its title, where and when it was published, and which page you used — but place them differently. Use one system for the whole paper. If your course uses a different style altogether, the APA citation guide and the MLA citation guide cover those.

Notes-bibliography vs author-date: which Chicago system to use

Your assignment brief decides. If it just says “Chicago,” your discipline is the usual guide: history, literature, religion, music and philosophy papers generally use notes-bibliography, while the sciences that use Chicago tend toward author-date. When unsure, ask before you start; converting a finished paper means rewriting every citation.

The systems suit different evidence. Notes-bibliography handles archival documents, letters and manuscripts that do not fit neatly into a parenthesis, and a note has room for a sentence of commentary — explaining that two sources disagree about a date, for instance. Author-date suits work built on recent studies, where the reader wants to see at a glance how current each source is.

How Chicago footnotes work

In notes-bibliography, each time you quote, paraphrase or rely on a source, you place a superscript number in your sentence and a matching note at the foot of the page (a footnote) or the end of the paper (an endnote). Numbers run consecutively through the paper and are never reused, even for a source cited again. The number goes at the end of the clause, after any punctuation mark except a dash.

The first note for a source gives full details. After that, a shortened note does the job: the author's surname, a short title of no more than four words, and the page. Some instructors accept shortened notes from the first citation when the paper has a full bibliography; confirm before relying on that. To add a note:

1. 1Put the cursor after the quotation or at the end of the clause that uses the source, after the comma or period.
2. 2Insert the note with your word processor's footnote tool, so the numbering updates when you add or delete notes.
3. 3For the first citation, write a full note: the author's name in normal order, the title, the publication facts in parentheses, then the page.
4. 4For later citations of the same source, write a shortened note: surname, short title, page.
5. 5Add the source to the bibliography, first author's name inverted, periods between the main elements.
6. 6Before you submit, check that every source cited in a note appears in the bibliography with matching details.

Chicago citation examples: notes and bibliography

Each example shows the full note, the shortened note and the bibliography entry. Italics cannot be shown here: italicize book and journal titles, and put article, chapter and webpage titles in quotation marks. Notes separate elements with commas and put publication facts in parentheses; bibliography entries use periods and invert the first author's name. For more source types, see the guides to citing a book and citing a website in APA, MLA and Chicago.

Chicago author-date citations and the reference list

In author-date, the in-text citation gives the author's surname and the year, then a comma and a page when you quote or point to a specific passage: (Hardin 1968, 1244). Unlike APA, there is no comma between name and year. If you name the author in your sentence, put the year in parentheses right after the name: Hardin (1968, 1244).

The reference list carries the same information as a bibliography with one change: the year moves up to sit right after the author's name, so a reader looking for (Hardin 1968) finds it instantly. The examples above become Tuchman, Barbara W. 1962. The Guns of August. New York: Macmillan. and Hardin, Garrett. 1968. “The Tragedy of the Commons.” Science 162, no. 3859: 1243–48. https://doi.org/10.1126/science.162.3859.1243. List several works by one author by year, earliest first. In-text citations change with the number of authors and sources:

• Two authors: (Lee and Park 2019, 12).
• Three authors: (Lee, Park, and Ortiz 2019).
• Four or more authors: (Lee et al. 2019), with the authors written out in the reference list.
• Two sources at once: (Hardin 1968; Tuchman 1962).
• Two works by one author from the same year: (Lee 2019a, 2019b), with matching letters in the reference list.

Formatting the bibliography and handling several authors

Start the list on a new page at the end of the paper, titled Bibliography for notes-bibliography or References for author-date. Arrange entries alphabetically by the first author's surname, each with a half-inch hanging indent. Student guides based on Chicago, Turabian among them, usually single-space each entry with a blank line between entries; your instructor's spacing rules come first.

Multiple authors are where notes and the bibliography differ most. Only the first author's name is inverted in a bibliography entry, and the serial comma comes before “and.”

Common Chicago citation mistakes

Most lost marks come from mixing the two systems or from APA and MLA habits. If your notes cite letters, archives or other documents, the guide to primary vs secondary sources shows how to tell them apart from later commentary. Check your draft for these:

• Mixing systems: footnotes in one section and parenthetical citations in another.
• Repeating the full note every time instead of shortening it after the first citation.
• Inverting the author's name in a note, or leaving it in normal order in the bibliography.
• Writing p. or pp. before page numbers in notes; Chicago normally gives the number alone.
• Placing the note number before a comma or period, not after.
• Adding a comma between name and year in author-date: write (Hardin 1968), not (Hardin, 1968).
• Dropping the place of publication from book entries; the 17th edition includes it, as in New York: Macmillan, 1962.