How to Cite Sources in Chicago Notes-Bibliography Style

The notes-bibliography system is one of two citation methods described in the Chicago Manual of Style (18th edition). It is the preferred format in history, philosophy, religious studies, and many areas of the humanities. Instead of placing author-date references in parentheses, you mark each citation with a superscript number and provide the full source details in a footnote or endnote. A bibliography at the end of the paper collects every source in alphabetical order.

This guide covers the core mechanics of the system - full notes, shortened notes, ibid., bibliography formatting, and worked examples for books, journal articles, websites, newspapers, and book chapters. If you want to skip the manual formatting, the AllCitations Chicago Notes generator can produce correctly formatted notes and bibliography entries from a URL, DOI, or ISBN. For a comparison of major styles, see our APA vs. MLA guide or browse all supported formats on the styles page.

How the Notes-Bibliography System Works

When you paraphrase, quote, or refer to a source, you place a superscript number at the end of the relevant sentence or clause. That number corresponds to a note - either a footnote at the bottom of the same page or an endnote collected at the end of the paper. The first time you cite a source, the note contains the full publication details. Every subsequent citation of the same source uses a shortened form.

At the end of the paper, a bibliography lists every source alphabetically by the author's last name. The bibliography entry is formatted differently from the note: most notably, the author's name is inverted (last name first) and periods replace commas as the primary separators.

The Chicago Manual of Style, 18th edition, covers the notes-bibliography system in Chapter 14. The student-focused companion, Kate Turabian's A Manual for Writers of Research Papers, Theses, and Dissertations, follows the same rules.

Footnotes vs. Endnotes

Chicago style permits either footnotes or endnotes. Footnotes appear at the bottom of the page where the citation occurs, making it easy for readers to check sources without flipping pages. Endnotes are grouped together at the end of the document (before the bibliography), which keeps the page layout cleaner. Your instructor or publisher will usually specify which to use. When no preference is stated, footnotes are the more common choice in history and the humanities.

Full Notes, Shortened Notes, and Ibid.

Full Note (First Citation)

The first time you cite a source, the note must include the complete publication information. The exact format varies by source type, but the general pattern for a book is:

1. First Name Last Name, Title of Book (Place of Publication: Publisher, Year), page number.

Note that the author's name appears in normal order (first name, then last name) in footnotes and endnotes. The inverted form (last name first) is reserved for bibliography entries.

Shortened Note (Subsequent Citations)

After the first full citation, every later reference to the same source uses a shortened form containing only the author's last name, a brief version of the title, and the page number:

2. Last Name, Shortened Title, page number.

The shortened title should be distinctive enough for the reader to locate the full entry in the bibliography. For a book titled The Architecture of Memory in Postwar Fiction, a shortened form like Architecture of Memory is sufficient. The Chicago Manual of Style, 18th edition, Section 14.29 describes the rules for constructing shortened notes.

Ibid.

When the same source is cited in two consecutive notes, you may use "Ibid." (from the Latin ibidem, meaning "in the same place") instead of repeating the shortened note:

3. Ibid., 98.

If both the source and the page number are the same as the preceding note, use "Ibid." alone without a page number. Chicago 18th edition (Section 14.34) notes that ibid. is optional - you may always use the shortened form instead. Many instructors and publishers now prefer shortened notes over ibid. because they remain clear even when notes are rearranged during editing.

Worked Examples

Below are worked examples for five common source types. Each example includes the full note, the shortened note, and the bibliography entry.

Book (Single Author)

Full note:

1. Jill Lepore, These Truths: A History of the United States (New York: W. W. Norton, 2018), 412.

Shortened note:

2. Lepore, These Truths, 420.

Bibliography entry:

Lepore, Jill. These Truths: A History of the United States. New York: W. W. Norton, 2018.

Key differences between the note and the bibliography entry: the bibliography inverts the author's name, uses periods instead of commas as the main separators, and omits the specific page number.

Journal Article

Full note:

3. Sarah Chen and Michael Torres, "Immigration Policy and Labor Markets in the European Union," Journal of Economic History 84, no. 2 (2024): 215-240.

Shortened note:

4. Chen and Torres, "Immigration Policy," 220.

Bibliography entry:

Chen, Sarah, and Michael Torres. "Immigration Policy and Labor Markets in the European Union." Journal of Economic History 84, no. 2 (2024): 215-240.

For journal articles, the note includes the specific page you are referencing, while the bibliography entry includes the full page range of the article. Article titles appear in quotation marks; journal titles are italicized.

Website

Full note:

5. World Health Organization, "Mental Health in the Workplace," World Health Organization, last modified March 10, 2025, https://www.who.int/example.

Shortened note:

6. World Health Organization, "Mental Health in the Workplace."

Bibliography entry:

World Health Organization. "Mental Health in the Workplace." Last modified March 10, 2025. https://www.who.int/example.

For websites, include the page title in quotation marks, the name of the website (if different from the author), a publication or modification date when available, and the URL. If no date is available, include an access date instead: "Accessed April 1, 2026."

Newspaper Article

Full note:

7. David Brooks, "The Philosophy of Data," New York Times, February 4, 2013.

Shortened note:

8. Brooks, "Philosophy of Data."

Bibliography entry:

Brooks, David. "The Philosophy of Data." New York Times, February 4, 2013.

Chicago 18th edition (Section 14.191) notes that newspaper articles may be cited in notes only, without a bibliography entry, especially when they are cited infrequently. If you cite several articles from the same newspaper, it is good practice to include them in the bibliography.

Chapter in an Edited Book

Full note:

9. Martha Nussbaum, "Patriotism and Cosmopolitanism," in For Love of Country: Debating the Limits of Patriotism, ed. Joshua Cohen (Boston: Beacon Press, 1996), 3-17.

Shortened note:

10. Nussbaum, "Patriotism and Cosmopolitanism," 10.

Bibliography entry:

Nussbaum, Martha. "Patriotism and Cosmopolitanism." In For Love of Country: Debating the Limits of Patriotism, edited by Joshua Cohen, 3-17. Boston: Beacon Press, 1996.

Note the structural difference: in the note, "ed." (lowercase) introduces the editor; in the bibliography entry, "edited by" is spelled out.

Building the Bibliography

The bibliography appears on a new page at the end of the paper with the centered heading "Bibliography." Entries are listed alphabetically by the first element, which is usually the author's last name. Key formatting rules from the Chicago Manual of Style, 18th edition (Sections 14.56-14.65):

• Indentation: Use a hanging indent - the first line of each entry is flush left, and subsequent lines are indented 0.5 inches.
• Spacing: Double-space all entries (unless your instructor specifies single spacing between entries with a blank line between them, which some Chicago-style guides allow).
• Author names: Invert only the first author's name (Last, First). Second and subsequent authors appear in normal order (First Last), joined by "and."
• Periods as separators: Unlike notes, which use commas, bibliography entries use periods to separate the three main blocks: author, title, and publication information.
• Alphabetization: Ignore "A," "An," and "The" at the start of a title when alphabetizing by title (for works with no author).

Multiple Works by the Same Author

When you list more than one work by the same author, replace the author's name with a 3-em dash after the first entry. Arrange the works chronologically, earliest first:

Lepore, Jill. The Name of War: King Philip's War and the Origins of American Identity. New York: Vintage Books, 1999.

---. These Truths: A History of the United States. New York: W. W. Norton, 2018.

Common Mistakes

Confusing note format with bibliography format. The most frequent error is using the bibliography's inverted-name style in footnotes or using the note's comma-separated style in the bibliography. Remember: notes use normal name order and commas; bibliography entries use inverted name order and periods.

Forgetting to shorten subsequent notes. After the first full note, every later citation of the same source should use the shortened form. Repeating the full note each time is not wrong per se, but it is unnecessarily verbose and does not follow Chicago convention.

Misusing ibid. after intervening notes. Ibid. may only be used when the immediately preceding note cites the same source. If another source has been cited in between, you must use the shortened note form, not ibid.

Omitting page numbers in notes. Whenever you are citing a specific passage, include the page number in the note. The bibliography entry does not include a specific page number (except for the full page range of an article or chapter), but notes should always point the reader to the exact location.

Using the wrong capitalization for titles. Chicago notes-bibliography style uses headline-style capitalization (also called title case) for English-language titles. This means capitalizing the first and last words and all major words. Articles, prepositions, and conjunctions are lowercase unless they begin the title.

Omitting URLs for online sources. If you accessed a source online, include the URL or DOI. A DOI is preferred when available because it is a permanent identifier. Format DOIs as full hyperlinks: https://doi.org/10.xxxx/example.

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