Chicago Citation Style: Notes, Bibliography, and Author-Date

Chicago style (The Chicago Manual of Style) is used in history, arts, literature, and some social sciences. It has two systems: Notes-Bibliography (N-B) and Author-Date. Use whichever your instructor or journal requires.

The two systems

Notes-Bibliography — used in humanities (history, literature, arts)

• Citations appear in numbered footnotes or endnotes
• A bibliography page lists all cited sources at the end
• In-text: superscript numbers (¹)

Author-Date — used in physical, natural, and social sciences

• Citations appear parenthetically in the text
• A reference list appears at the end
• In-text: (Author Year, page)

Notes-Bibliography: footnotes

Each citation in the text gets a superscript number. The full citation appears at the bottom of the page (footnote) or at the end of the paper (endnote).

First footnote — single author book:

1. Daniel Kahneman, Thinking, Fast and Slow (New York: Farrar, Straus and Giroux, 2011), 47.

Subsequent footnote for same source (shortened):

2. Kahneman, Thinking, Fast and Slow, 52.

Or use ibid. if citing the same source consecutively:

3. Ibid., 55.

Note: Chicago 17 recommends using the shortened form over ibid. for clarity.

Journal article footnote:

4. Alaknanda Bagchi, "Conflicting Nationalisms: The Voice of the Subaltern in Mahasweta Devi's Bashai Tudu," Tulsa Studies in Women's Literature 15, no. 1 (1996): 42.

Website footnote:

5. James Roberts, "How Neural Networks Learn," Towards Data Science, November 12, 2025, https://towardsdatascience.com/how-neural-networks-learn.

Notes-Bibliography: bibliography

The bibliography uses a different format from footnotes — last name first, full stop instead of comma before year for books:

Book:

Kahneman, Daniel. Thinking, Fast and Slow. New York: Farrar, Straus and Giroux, 2011.

Two authors:

Strunk, William, Jr., and E. B. White. The Elements of Style. 4th ed. New York: Longman, 1999.

Three or more authors:

Wysocki, Anne Frances, Johndan Johnson-Eilola, Cynthia Selfe, and Geoffrey Sirc. Writing New Media. Logan: Utah State UP, 2004.

Edited book:

Peterson, Christopher, and Martin E. P. Seligman, eds. Character Strengths and Virtues. New York: Oxford University Press, 2004.

Chapter in edited book:

Bjork, Robert A. "Retrieval Inhibition as an Adaptive Mechanism in Human Memory." In Varieties of Memory and Consciousness, edited by Henry L. Roediger and Fergus I. M. Craik, 309–330. Hillsdale, NJ: Erlbaum, 1989.

Journal article:

Bagchi, Alaknanda. "Conflicting Nationalisms: The Voice of the Subaltern in Mahasweta Devi's Bashai Tudu." Tulsa Studies in Women's Literature 15, no. 1 (1996): 41–50.

Website:

Roberts, James. "How Neural Networks Learn." Towards Data Science. November 12, 2025. https://towardsdatascience.com/how-neural-networks-learn.

No author — website:

"Global Chip Shortage Explained." BBC News. March 3, 2026. https://bbc.com/news/technology-56252495.

Author-Date system

In-text citations

(Kahneman 2011, 47)
(Strunk and White 1999)
(Wysocki et al. 2004, 12)

For three or more authors, use “et al.” in the in-text citation.

Reference list

The reference list is similar to the bibliography but with the year moved after the author:

Book:

Kahneman, Daniel. 2011. Thinking, Fast and Slow. New York: Farrar, Straus and Giroux.

Journal article:

Bagchi, Alaknanda. 1996. "Conflicting Nationalisms: The Voice of the Subaltern in Mahasweta Devi's Bashai Tudu." Tulsa Studies in Women's Literature 15 (1): 41–50.

Website:

Roberts, James. 2025. "How Neural Networks Learn." Towards Data Science. November 12, 2025. https://towardsdatascience.com/how-neural-networks-learn.

Turabian style

Turabian (A Manual for Writers of Research Papers, Theses, and Dissertations) is based on Chicago and follows the same two systems. The main differences are minor formatting adjustments for student papers (running head, page numbers, etc.). For citation format, Turabian and Chicago are interchangeable.

Footnote vs. endnote

Both use superscript numbers and follow the same citation format. The difference is placement:

• Footnote — at the bottom of the page where the citation appears
• Endnote — collected at the end of the paper or chapter

Most word processors (Word, Google Docs) handle footnote numbering automatically. Check your assignment requirements — some instructors prefer one over the other.

Common mistakes in Chicago style

Using the same format for footnotes and bibliography: Footnotes use commas and put the year near the end; bibliography entries use periods and put the year after the publisher. They’re not the same.

Forgetting ibid. rules: Chicago 17 recommends shortened forms over ibid. — check your instructor’s preference.

Omitting the city for books: Chicago (unlike APA 7) still requires the publisher’s city for books.

Wrong system for the discipline: History uses N-B; sociology uses Author-Date. Check which system your instructor or journal requires.

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