Chicago Citation Format Guide
The Chicago Manual of Style (CMOS) is one of the most comprehensive and widely used style guides in the United States. It is the standard for history, art history, literature, and many humanities disciplines, and it is commonly used in publishing and journalism. Chicago style offers two distinct citation systems: Notes-Bibliography (NB), used primarily in humanities, and Author-Date (AD), used in sciences and social sciences. This guide covers both systems.
Format Rules
Notes-Bibliography vs. Author-Date
Notes-Bibliography uses superscript numbers in the text that correspond to footnotes or endnotes, plus a bibliography at the end. It is favored in the humanities because notes allow for commentary alongside citations. Author-Date uses parenthetical citations (Author Year, page) similar to APA and a reference list at the end. It is preferred in the sciences.
Footnotes and Endnotes
In Notes-Bibliography style, insert a superscript number at the end of the relevant sentence. Notes can be footnotes (at the bottom of the page) or endnotes (on a separate page at the end). The first reference to a source is a full citation; subsequent references use a shortened form (author last name, shortened title, page). Use 'Ibid.' only for back-to-back citations of the same source.
Paper Formatting
Chicago papers use 1-inch margins on all sides, 12pt Times New Roman or similar font, and double-spacing for body text. Footnotes are single-spaced with a blank line between them. The bibliography and reference list also use single-spacing within entries and double-spacing between entries, with a hanging indent.
Title Page
Chicago style papers typically include a title page with the paper title (centered, about one-third from the top), the author's name, the course name and number, the instructor's name, and the date — all centered. Page numbers begin on the first page of the text (not the title page), usually in the top-right header.
Bibliography Formatting
The bibliography appears at the end of the paper on a new page with the centered heading "Bibliography." Entries are listed alphabetically by the author's last name. Use a hanging indent. Unlike footnotes, bibliography entries list last name first. Separate elements with periods rather than commas.
Differences in Author-Date Style
In Author-Date citations, place the author's last name, year, and page number in parentheses directly in the text: (Smith 2018, 45). The reference list is formatted similarly to the bibliography but with the publication year immediately after the author's name. Titles follow sentence case rather than title case.
Shortened Citations in Notes
After the first full footnote or endnote for a source, subsequent citations use a shortened form: Author Last Name, Shortened Title, Page Number. Example: First note: John Smith, <i>The History of Everything</i> (Oxford University Press, 2020), 34. Subsequent note: Smith, <i>History of Everything</i>, 67.
Capitalization Rules
Chicago uses title case for most titles in Notes-Bibliography style: capitalize the first and last words and all major words (nouns, verbs, adjectives, adverbs). In Author-Date style, use sentence case for article and chapter titles (capitalize only the first word and proper nouns) but keep title case for journal names and book titles.
Citation Examples
Tuchman, Barbara. The Guns of August. Ballantine Books, 1962.
Notes-Bibliography: Footnote: Barbara Tuchman, The Guns of August (Ballantine Books, 1962), 12. Bibliography: Tuchman, Barbara. The Guns of August. Ballantine Books, 1962. Author-Date: In-text: (Tuchman 1962, 12) Reference: Tuchman, Barbara. 1962. The Guns of August. Ballantine Books.
Acemoglu, Daron, and James A. Robinson. Why Nations Fail. Crown Publishers, 2012.
Notes-Bibliography: Footnote: Daron Acemoglu and James A. Robinson, Why Nations Fail (Crown Publishers, 2012), 76. Bibliography: Acemoglu, Daron, and James A. Robinson. Why Nations Fail. Crown Publishers, 2012. Author-Date: In-text: (Acemoglu and Robinson 2012, 76) Reference: Acemoglu, Daron, and James A. Robinson. 2012. Why Nations Fail. Crown Publishers.
Davis, Angela Y. "Reflections on the Black Woman's Role in the Community of Slaves." The Massachusetts Review 13, no. 1/2 (1972): 81–100.
Notes-Bibliography: Footnote: Angela Y. Davis, "Reflections on the Black Woman's Role in the Community of Slaves," The Massachusetts Review 13, no. 1/2 (1972): 85. Bibliography: Davis, Angela Y. "Reflections on the Black Woman's Role in the Community of Slaves." The Massachusetts Review 13, no. 1/2 (1972): 81–100. Author-Date: In-text: (Davis 1972, 85) Reference: Davis, Angela Y. 1972. "Reflections on the Black Woman's Role in the Community of Slaves." The Massachusetts Review 13 (1/2): 81–100.
Walsh, Mary. "The Hidden Costs of Food Waste." The Atlantic, March 3, 2024. https://www.theatlantic.com/food-waste.
Notes-Bibliography: Footnote: Mary Walsh, "The Hidden Costs of Food Waste," The Atlantic, March 3, 2024, https://www.theatlantic.com/food-waste. Bibliography: Walsh, Mary. "The Hidden Costs of Food Waste." The Atlantic. March 3, 2024. https://www.theatlantic.com/food-waste. Author-Date: In-text: (Walsh 2024) Reference: Walsh, Mary. 2024. "The Hidden Costs of Food Waste." The Atlantic. March 3, 2024. https://www.theatlantic.com/food-waste.
"Coral Reef Ecosystems." NOAA Fisheries. Accessed January 10, 2025. https://www.fisheries.noaa.gov/topic/coral-reef-ecosystems.
Notes-Bibliography: Footnote: "Coral Reef Ecosystems," NOAA Fisheries, accessed January 10, 2025, https://www.fisheries.noaa.gov/topic/coral-reef-ecosystems. Bibliography: "Coral Reef Ecosystems." NOAA Fisheries. Accessed January 10, 2025. https://www.fisheries.noaa.gov/topic/coral-reef-ecosystems.
Kolbert, Elizabeth. "A Song of Ice." The New Yorker, October 24, 2016.
Notes-Bibliography: Footnote: Elizabeth Kolbert, "A Song of Ice," The New Yorker, October 24, 2016. Bibliography: Kolbert, Elizabeth. "A Song of Ice." The New Yorker. October 24, 2016. Author-Date: In-text: (Kolbert 2016) Reference: Kolbert, Elizabeth. 2016. "A Song of Ice." The New Yorker, October 24.
Coppola, Francis Ford, dir. The Godfather. Paramount Pictures, 1972.
Notes-Bibliography: Footnote: Francis Ford Coppola, dir., The Godfather (Paramount Pictures, 1972). Bibliography: Coppola, Francis Ford, dir. The Godfather. Paramount Pictures, 1972. Author-Date: In-text: (Coppola 1972) Reference: Coppola, Francis Ford, dir. 1972. The Godfather. Paramount Pictures.
Gladwell, Malcolm. "The Foot Soldier of Birmingham." Revisionist History, podcast audio, August 13, 2016. http://revisionisthistory.com.
Notes-Bibliography: Footnote: Malcolm Gladwell, "The Foot Soldier of Birmingham," Revisionist History, podcast audio, August 13, 2016, http://revisionisthistory.com. Bibliography: Gladwell, Malcolm. "The Foot Soldier of Birmingham." Revisionist History. Podcast audio, August 13, 2016. http://revisionisthistory.com.
Morrison, Toni. "Rootedness: The Ancestor as Foundation." In Black Women Writers (1950–1980): A Critical Evaluation, edited by Mari Evans, 339–45. Anchor Press/Doubleday, 1984.
Notes-Bibliography: Footnote: Toni Morrison, "Rootedness: The Ancestor as Foundation," in Black Women Writers (1950–1980): A Critical Evaluation, ed. Mari Evans (Anchor Press/Doubleday, 1984), 341. Bibliography: Morrison, Toni. "Rootedness: The Ancestor as Foundation." In Black Women Writers (1950–1980): A Critical Evaluation, edited by Mari Evans, 339–45. Anchor Press/Doubleday, 1984.