Chicago Style Format: The Complete Guide
Updated June 2026
Chicago style — from The Chicago Manual of Style, 17th edition — is the standard for history, art history, and much of publishing. Its defining feature is that it offers two different systems, and choosing the right one is the first thing you must do.
This guide covers both systems, the paper-formatting rules they share, and the entry formats for the sources you'll actually cite — with every example generated by the same engine that powers the Chicago citation generator.
The two Chicago systems — pick one first
Chicago is really two citation styles under one cover, and they don't mix. Your discipline decides which you use:
- Notes-Bibliography (NB) — superscript numbers in the text point to footnotes (or endnotes), with a matching Bibliography at the end. Used in history, literature, and the arts. This is what most people mean by "Chicago."
- Author-Date — parenthetical (Author Year, page) citations in the text, with a Reference List at the end — structurally almost identical to APA. Used in the sciences and social sciences.
Paper formatting rules (both systems)
- Margins: 1 inch on all sides. Font: a readable, consistent choice — 12pt Times New Roman is the safe default.
- Spacing: double-space the body; footnotes and bibliography entries are single-spaced internally with a blank line between them.
- Title page: title centered about a third of the way down, then your name, course, and date lower on the page. (Chicago papers usually use a title page rather than a heading block.)
- Page numbers: top-right or bottom-center, starting on the first page of text (the title page is unnumbered).
- Block quotes: quotations of five or more lines (or 100+ words) are blocked — indented, no quotation marks.
Notes-Bibliography: footnotes and the bibliography
Note (first): 1. Robert C. Martin, Clean Code (Upper Saddle River: Prentice Hall, 2008), 45. Bibliography: Martin, Robert C. Clean Code. Upper Saddle River: Prentice Hall, 2008.
In NB, the first note for a source is full; later notes are shortened (author surname, short title, page). The bibliography entry holds the same facts in a different shape — author inverted, periods instead of commas. The full mechanics, including ibid. and short-note rules, are in Chicago Footnotes.
Author-Date: in-text and reference list
The author-date system cites parenthetically — (Rasch and Born 2013, 685) — and lists full entries in a Reference List, alphabetized by surname. The year moves up next to the author (as in APA), and the entry uses commas and parentheses differently from the NB bibliography. If your instructor wants parenthetical citations rather than footnotes, this is the system you want.
Bibliography entry formats by source
The three formats that cover most papers, generated by our engine exactly as the generator produces them (notes-bibliography shape):
Martin, Robert C. Clean Code: A Handbook of Agile Software Craftsmanship. Prentice Hall, 2008.
Rasch, Björn, and Jan Born. "About sleep's role in memory." Physiological Reviews 93, no. 2 (2013): 681-766. https://doi.org/10.1152/physrev.00032.2012.
Alvarez, Maria. "How memory consolidation works during sleep." Science Daily. March 18, 2024. https://www.sciencedaily.com/memory-consolidation-sleep.
Which system should you use?
Notes-Bibliography if your field is history, art history, philosophy, religion, or literature — or any time your instructor mentions "footnotes." Author-Date if you're in the sciences or social sciences, or your instructor asks for parenthetical citations. When a syllabus just says "Chicago" with no other detail, it almost always means Notes-Bibliography. Still unsure how Chicago compares to the alternatives? See How to Choose a Citation Style.
Common Chicago mistakes
For any case this guide doesn't cover — multivolume works, manuscripts, primary sources — the Chicago Manual of Style Online is the authoritative source, and Purdue OWL's Chicago guide is the best free secondary reference.
- Mixing the two systems — footnotes and parenthetical author-date in the same paper. Pick one.
- Note vs. bibliography shape — a note is not inverted and uses commas; the bibliography entry inverts the first author and uses periods. They are not interchangeable.
- Forgetting the shortened note — every note after the first should be the short form, not a repeat of the full citation.
- Publisher location — unlike APA 7, Chicago still includes the city of publication for books.
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Go Premium — $5/monthFrequently asked questions
- What's the difference between Chicago's two systems?
- Notes-Bibliography uses superscript numbers and footnotes plus a bibliography (history and the humanities). Author-Date uses parenthetical (Author Year) citations and a reference list (the sciences). They are not mixed in one paper.
- Is Chicago the same as Turabian?
- Turabian is a student-focused simplification of Chicago by Kate Turabian — same two systems, lightly streamlined for coursework. A correct Chicago citation is generally acceptable where Turabian is requested.
- Does Chicago still include the publisher's city?
- Yes — unlike APA 7 (which dropped it), Chicago book citations still name the city of publication before the publisher.
- Footnotes or endnotes?
- Either — they contain identical content. Footnotes sit at the bottom of the page; endnotes collect at the end of the document. Follow your instructor's or publisher's preference.