Chicago Style Citation Guide: Two Systems Made Simple
Chicago style — set out in The Chicago Manual of Style (CMOS) — is the standard in history, the humanities, and many social sciences. Unlike APA and MLA, which use a single in-text format, Chicago offers two distinct systems. Choosing the right one is the first thing your instructor will check. This guide walks you through both, with copy-ready examples for the sources you cite most.
The Two Chicago Systems at a Glance
| Notes–Bibliography (NB) | Author–Date | |
|---|---|---|
| Used in | History, art, literature, philosophy | Sciences, social sciences |
| In-text marker | Superscript number¹ → footnote/endnote | (Author Year, page) |
| Source list title | Bibliography | References |
| Best when | You cite varied sources (archives, letters) | You cite mostly studies and data |
If your assignment just says "use Chicago" with no further detail, Notes–Bibliography is the safer default for humanities courses. When in doubt, ask — using the wrong system is one of the most common reasons papers lose formatting marks.
System 1: Notes–Bibliography
You place a superscript number at the end of the sentence you are citing. That number points to a footnote (bottom of the page) or endnote (end of the document), and the same source also appears in your Bibliography.
Book
First footnote (full):
- Jill Lepore, These Truths: A History of the United States (New York: W. W. Norton, 2018), 142.
Shortened note (every time after the first):
- Lepore, These Truths, 207.
Bibliography entry (note the inverted author name and periods instead of commas):
Lepore, Jill. These Truths: A History of the United States. New York: W. W. Norton, 2018.
Journal Article
Footnote:
- Caroline Winterer, "Where Is America in the Republic of Letters?," Modern Intellectual History 9, no. 3 (2012): 600.
Bibliography:
Winterer, Caroline. "Where Is America in the Republic of Letters?" Modern Intellectual History 9, no. 3 (2012): 597–623.
Website
Footnote:
- "About AcademicTuning," AcademicTuning, accessed June 28, 2026, https://academictuning.com/about.
Bibliography:
AcademicTuning. "About AcademicTuning." Accessed June 28, 2026. https://academictuning.com/about.
System 2: Author–Date
Here you cite the source in parentheses right in the text, and list full details in a References list. This is closer to APA, so if you have used APA before it will feel familiar.
In-text citation:
The frontier thesis shaped a generation of historians (Turner 1893, 199).
Reference-list entries:
Book:
Lepore, Jill. 2018. These Truths: A History of the United States. New York: W. W. Norton.
Journal article:
Winterer, Caroline. 2012. "Where Is America in the Republic of Letters?" Modern Intellectual History 9 (3): 597–623.
Notice the differences from NB: the year moves up next to the author, and the parenthetical issue number replaces "no. 3."
Chicago vs. Turabian — Are They the Same?
Almost. A Manual for Writers by Kate Turabian is the student-focused adaptation of CMOS. The citation rules are essentially identical; Turabian simply adds guidance on margins, title pages, and headings aimed at coursework, theses, and dissertations. If your professor says "Turabian," follow this guide and apply your department's page-layout requirements.
Page Formatting Essentials
- Font: A readable serif such as Times New Roman, 12 pt.
- Spacing: Double-space the body; single-space footnotes and bibliography entries, with a blank line between entries.
- Margins: 1 inch on all sides.
- Page numbers: Top right, or bottom center — be consistent.
- Bibliography/References: New page, title centered, entries alphabetized by author surname with a hanging indent.
For the full manuscript structure — title page, headings, and section order — see our research paper format guide.
Five Common Chicago Mistakes
- Mixing the two systems. Footnotes and author–date parentheticals in the same paper signal you did not pick a system. Choose one.
- Never shortening notes. Only the first note for a source is full; every later note uses the short form (author surname, short title, page).
- Comma vs. period confusion. Footnotes use commas between elements; bibliography entries use periods. They are not interchangeable.
- Forgetting the access date for online sources without a publication date.
- Wrong page-range style. Bibliography entries list the full range (597–623); footnotes cite only the specific page you used (600).
Frequently Asked Questions
Which Chicago edition should I use? Most courses now use the 17th edition; the 18th edition (2024) is being adopted gradually. The citation examples above are valid in both — confirm the required edition with your instructor.
Do I need both footnotes and a bibliography? In Notes–Bibliography style, yes — most instructors require both. The notes document specific claims; the bibliography gives the reader the complete source list.
Can I cite the same source twice? Yes. Use the full note the first time and the shortened note afterward. The source appears only once in the bibliography.
Is Chicago harder than APA or MLA? It has more moving parts because of the two systems and footnotes, but the logic is consistent. Compare with our APA 7th edition guide and MLA formatting guide to see which feels most natural for your field.
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