The Official Source

The Chicago Manual of Style, 18th Edition (2024) is published by the University of Chicago Press and available in hardcover and online at chicagomanualofstyle.org.

The 18th edition—the most extensive revision in two decades—introduced guidance on citing AI-generated content, expanded inclusive language coverage, updated capitalization rules, and no longer requires publication locations in citations.

Two Citation Systems

Chicago offers two documentation styles:

1. Notes-Bibliography (NB) — Preferred in humanities (history, literature, arts)

2. Author-Date — Preferred in sciences and social sciences

This guide covers the Notes-Bibliography system, which uses footnotes or endnotes plus a bibliography.

Notes-Bibliography: Quick Overview

When you cite a source:

1. Place a superscript number after the relevant text¹

2. Include the full citation in a footnote or endnote

3. List all sources in a bibliography at the end

Footnote vs. Bibliography Format

Footnotes and bibliography entries differ slightly in format:

Book

Footnote (first reference):

1. Ta-Nehisi Coates, Between the World and Me (New York: One World, 2015), 45.

Shortened footnote (subsequent references):

2. Coates, Between the World and Me, 52.

Bibliography:

Coates, Ta-Nehisi. Between the World and Me. New York: One World, 2015.

Key differences: Footnotes use first name first with commas; bibliographies invert the first author's name and use periods.

Common Source Examples

Journal Article

Footnote:

1. Susan Sontag, "Notes on 'Camp,'" Partisan Review 31, no. 4 (1964): 517.

Bibliography:

Sontag, Susan. "Notes on 'Camp.'" Partisan Review 31, no. 4 (1964): 515–30.

Chapter in Edited Book

Footnote:

1. bell hooks, "Eating the Other," in Black Looks: Race and Representation (Boston: South End Press, 1992), 21.

Bibliography:

hooks, bell. "Eating the Other." In Black Looks: Race and Representation, 21–39. Boston: South End Press, 1992.

Website

Footnote:

1. "Privacy Policy," Google, last modified April 17, 2024, https://policies.google.com/privacy.

Bibliography:

Google. "Privacy Policy." Last modified April 17, 2024. https://policies.google.com/privacy.

Newspaper Article

Footnote:

1. Jennifer Schuessler, "The Surprising History of 'Woke,'" The New York Times, October 12, 2023.

Bibliography:

Schuessler, Jennifer. "The Surprising History of 'Woke.'" The New York Times, October 12, 2023.

Key 18th Edition Changes

Major updates in the 2024 edition:

• No publication location — City/state no longer required for most sources

• "Title Case" renamed — Now officially called "headline-style capitalization"

• Preposition capitalization — Prepositions of five or more letters now capitalized in titles (About, Through, Without)

• Generic singular "they" — Fully endorsed for unknown or unspecified gender

• Initial "The" retained — Now capitalize and italicize when part of publication title (The New York Times)

• AI citations — New guidance for citing AI-generated text and images

• Ibid. discouraged — Shortened citations preferred over "ibid." for repeated sources

Shortened Citations

After citing a source once in full, use a shortened form for subsequent references:

First reference:

1. Michelle Alexander, The New Jim Crow: Mass Incarceration in the Age of Colorblindness (New York: New Press, 2010), 73.

Subsequent references:

5. Alexander, New Jim Crow, 89.

The 18th edition discourages using "ibid." due to electronic publishing formats where footnotes may not appear sequentially.

Common Mistakes to Avoid

Commas vs. periods — Use commas between elements in footnotes; use periods in bibliography entries

Author name order — First name first in footnotes; last name first in bibliography (only for the first author)

Page numbers — Include specific pages in footnotes; include full page range in bibliography

Quotation marks vs. italics — Article and chapter titles in quotes; book, journal, and website titles in italics

Multiple authors — In bibliography, invert only the first author's name

Who Uses Chicago Style?

Chicago is the standard for:

• History

• Art history

• Philosophy

• Religion and theology

• Some social sciences

• Publishing industry

Many academic presses and scholarly journals require Chicago style. Students in these fields should master both the Notes-Bibliography and Author-Date systems.

Chicago vs. Turabian

A Manual for Writers by Kate Turabian presents a simplified version of Chicago style designed for students. Turabian and Chicago are largely compatible, but always check which your instructor requires.

Further Resources

• Chicago Manual of Style Online — Subscription-based access with Q&A

• CMOS Citation Quick Guide — Free quick reference

• Purdue OWL Chicago Guide — Free comprehensive resource

Need help generating Chicago citations? Research tools like Wonders can export your sources in Chicago format automatically.