Chicago style is used in many history, arts, and humanities courses, and it also offers an author-date system used in some social and scientific fields. Before formatting a paper, identify which Chicago system your instructor wants. The 18th edition was published in 2024, and citation details should be checked against the edition or guide assigned for your course.
Chicago has two citation systems
The Notes and Bibliography system places a numbered footnote or endnote in the text and provides source details in the note. A bibliography usually appears at the end. It is especially useful when a paper relies on historical documents, archival materials, books, and other varied sources.
The Author-Date system places an author and year in parentheses, usually with a page number when citing a specific passage. A matching reference list provides the full information. The system looks similar to author-date styles such as APA, but the exact punctuation and entry format are not interchangeable.
Do not decide between the two systems yourself when the course already specifies one. If the syllabus only says “Chicago,” check an example or ask which system is expected.
- Notes and Bibliography: note numbers plus bibliography.
- Author-Date: parenthetical author-date citations plus references.
- Both systems have specific rules for books, articles, websites, interviews, images, and other source types.
How Chicago footnotes work
In Notes and Bibliography style, insert the note number where the source is used, usually with the word processor’s footnote feature. The first note for a source generally provides fuller details; later notes can use a shortened form. Each note should let the reader identify the work and, where relevant, the location of the cited material.
The following is an illustrative fictional book example, not a real publication. Always compare the exact elements and punctuation with the Chicago guide and the source you actually used.
1. Morgan Lee, Learning in Public (North River Press, 2023), 42.
Shortened note: 2. Lee, Learning in Public, 45.- Use your word processor’s built-in footnote or endnote feature.
- Use a shortened note for repeated references where the guide permits it.
- Do not use “ibid.” automatically; current Chicago guidance favors shortened citations in many repeated-citation situations.
How to format a Chicago bibliography entry
A bibliography entry usually inverts the first author’s name so readers can find it alphabetically. Compared with a full note, the entry changes punctuation and the order of names and elements.
Here is a matching illustrative example for the same fictional book. In the 18th edition, a city of publication is generally no longer required in a book citation; check the current rules for your source type and assignment.
Lee, Morgan. Learning in Public. North River Press, 2023.- Put the bibliography after the main text and any appendices, unless your instructions specify otherwise.
- Alphabetize entries by the appropriate first element.
- Use a hanging indent if required by your instructor or formatting guide.
- Make sure every cited work appears in the bibliography when one is required.
Chicago Author-Date in-text citations
In the Author-Date system, the short citation typically includes the author’s surname, year, and—when needed—a page number. The full entry in the reference list must match the author and year in the text.
Using the fictional book above, a simplified citation for a specific page could look like (Lee 2023, 42). It is not the same as APA’s punctuation and should not be reformatted by intuition alone.
- Cite the source where you use its information.
- Include a page or other location when the style calls for it and the source provides one.
- Keep the reference list consistent with the in-text author and year.
Common Chicago style errors
Students often mix note-based and author-date systems, make the bibliography look like a footnote list, or repeat full source details where shortened notes are appropriate. The exact rules depend on the system and type of source.
Chicago formatting also changes by source type. A journal article, book chapter, web page, interview, and archival document do not share one universal template. Do not remove a field merely because it does not appear in an example for another source type.
- Confirm whether your assignment uses Notes and Bibliography or Author-Date.
- Use the required Chicago edition, especially for details changed between editions.
- Check publication details and page numbers against the original source.
- Use consistent note numbering and cross-check every cited source.
Where to verify Chicago 18th edition examples
The Chicago Manual of Style offers a citation quick guide with both Notes and Bibliography and Author-Date examples: https://www.chicagomanualofstyle.org/tools_citationguide.html. Purdue OWL also provides an introduction to the 18th edition at https://owl.purdue.edu/owl/research_and_citation/chicago_manual_18th_edition/chicago_manual_of_style_18th_edition.html.
Your department or library may provide an institutional guide. Use it to interpret local requirements, but check that it names the edition your instructor expects.
Final Chicago paper checklist
Chicago style becomes manageable once you identify the system, collect complete source information, and apply one source-type template at a time.
- I confirmed which Chicago system my instructor expects.
- I used the correct rules for the source type.
- Notes or parenthetical citations match the bibliography or reference list.
- Repeated notes use the appropriate shortened form.
- I checked the course instructions before submitting.
Understanding the concept is the first step.
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