What Chicago style is
Chicago style comes from The Chicago Manual of Style, one of the oldest and most comprehensive style guides in American publishing (the student-focused version is often called "Turabian", after Kate Turabian, who adapted it for coursework). It is widely used in history, art history, and parts of the humanities and social sciences, and it is prized for handling complicated source types — archival documents, multi-volume works, translated editions — with precision.
The defining feature of Chicago is that it offers two distinct documentation systems, and they work completely differently. Before you write a single citation, you must know which one your assignment requires, because converting between them later is tedious and error-prone.
Which system should you use?
| Notes–Bibliography | Author–Date | |
|---|---|---|
| How you cite | Superscript number → footnote | Parenthetical (Author Year) |
| List at the end | Bibliography | Reference List |
| Typical fields | History, literature, arts | Sciences, social sciences |
If your brief doesn't say, the convention of your discipline is the best guide: humanities students almost always use Notes–Bibliography, while science and social-science students use Author–Date. When in genuine doubt, ask your tutor — it is the kind of question they would much rather answer before you write than after.
Notes–Bibliography system
In this system you place a superscript number at the end of the sentence containing the borrowed material. That number corresponds to a footnote at the bottom of the page (or an endnote at the end of the document), which gives the full source and the specific page. You also include a Bibliography at the end listing every source alphabetically.
The footnote and the bibliography entry describe the same source but are punctuated differently — the footnote uses commas and gives a specific page, while the bibliography uses full stops, inverts the author's name for alphabetising, and omits the page reference for a whole book.
First (full) footnote
Matching bibliography entry
Short notes and ibid.
The first time you cite a source you give the full footnote above. Every time after that, you use a shortened note — the author's surname, a short form of the title, and the page:
You may also have seen ibid. ("in the same place") used when two consecutive notes cite the same source. The 17th edition of the Manual discourages ibid. in favour of the shortened note, partly because notes are often reordered during editing and ibid. then points to the wrong source. Use the short form and you will never be wrong.
More notes & bibliography examples
Chapter in an edited book (note / bibliography)
Journal article
Website (note)
Author–Date system
The Author–Date system will feel familiar if you know APA or Harvard. You cite the author and year in brackets in your text — (Lepore 2018, 212) — note there is no comma between author and year, and the page follows a comma. Every source then appears in a Reference List at the end.
The early republic was less unified than its founders claimed (Lepore 2018, 212), a point echoed in more recent surveys (Chen 2021, 19).
Author–Date reference examples
Book
Journal article
Notice that in Author–Date the year moves up to sit right after the author — exactly so the in-text "(Author Year)" cue can find it quickly — whereas in Notes–Bibliography the date sits later in the entry. That single difference is why you cannot simply paste a bibliography into a reference list; the element order changes.
Citing trickier sources
Chicago's reputation rests on how well it handles the awkward sources that humanities research throws up. These examples use the Notes–Bibliography form (the note first, then the bibliography entry where it differs).
Translated work
Multi-volume work
Primary or archival source
Online video
Notice how the note adapts to each source while keeping the same logic — creator, title, the container or repository, and a precise location (a page, a volume, a date, a timestamp). For genuinely unusual material, Chicago's principle is to give the reader enough information to find the exact item; when no template fits, describe the source clearly and consistently rather than forcing it into the wrong mould.
Formatting a Chicago paper
A typical Chicago/Turabian paper uses a readable 12-point font (Times New Roman is conventional), double-spaced body text, one-inch margins, and page numbers in the top-right or centre footer. Footnotes are single-spaced within each note. A separate title page carries the title roughly a third of the way down, with your name, course and date lower on the page. Block quotations (generally five or more lines) are single-spaced and indented, with no quotation marks. These conventions vary a little by institution, so — as ever — your department's guide is the final word.
The two systems at a glance
Both systems describe the same sources with the same information; they differ in mechanism, not in what counts as a source. Notes–Bibliography keeps the page clean and lets you add commentary inside footnotes (handy in history, where a note might add nuance). Author–Date keeps everything inline and is faster to scan for "who and when", which suits empirical work. Choose the one your field expects, and never mix them in one paper.
Quoting in Chicago
Quotation in Chicago follows the same logic in both systems: a short quotation runs into your sentence in double quotation marks, while a longer one — generally five lines or more — is set as a block quotation, indented and single-spaced, with no quotation marks. The citation (a footnote in Notes–Bibliography, a parenthetical reference in Author–Date) comes at the end, with a pinpoint to the exact page. Because history and the humanities argue closely from sources, the pinpoint matters: a footnote that cites a 300-page book without a page number does only half its job, and a marker will notice.
Chicago's footnote system has one quiet advantage for writers working with sources: the footnote can carry not just the citation but a brief comment — a note on the reliability of a source, a pointer to a contrasting account, or a translation of a quoted phrase. Used with restraint, this lets you keep your main argument clean while showing the marker the depth of your engagement with the evidence. The discipline is to keep such notes genuinely brief; a footnote that swells into a second essay distracts rather than supports.
As in every style, quotation should be purposeful. Quote when the exact words are the point — a contested phrase, a primary-source passage you intend to analyse, a definition that must be precise — and paraphrase, with a citation and pinpoint, everywhere else. Over-quotation makes an essay read as a scrapbook of other people's sentences; careful paraphrase, punctuated by well-chosen quotations, shows that you are thinking with your sources rather than merely collecting them.
Common mistakes to avoid
- Mixing footnotes (Notes–Bibliography) with parenthetical citations (Author–Date) in one paper.
- Overusing ibid. instead of a clearer shortened note.
- Giving a full footnote every time instead of switching to the short form after the first citation.
- Putting specific page numbers in a bibliography entry for a whole book (pages belong in the note, or in a chapter/article range).
- Forgetting that Author–Date moves the year up next to the author.
- Typing footnote numbers by hand instead of using your word processor's footnote tool.
Decide your system first, let your software handle the footnote numbering, and keep the full-note-then-short-note rhythm consistent. Do that and Chicago — for all its reputation — becomes very manageable. If a history essay's footnotes are eating your week, our writers can produce a fully referenced model in either Chicago system.
Chicago, Turabian and your course
Students are often told to use "Chicago" by one tutor and "Turabian" by another and assume they are two different systems to learn. They are not. A Manual for Writers of Research Papers, Theses, and Dissertations by Kate Turabian is essentially The Chicago Manual of Style adapted for students rather than professional publishers. It uses the same two systems — Notes–Bibliography and Author–Date — with the same mechanics covered above. The differences are small and practical: Turabian focuses on the needs of coursework and theses, simplifies a few publishing-specific rules, and gives clearer guidance on formatting a student paper.
So if your brief says "Turabian", everything in this guide still applies; you are simply using the student-facing edition of the same standard, and our dedicated Turabian guide covers the handful of points where it gives its own advice. The practical takeaway is reassuring: learn Chicago once and you have learned Turabian too. What still matters most is the first decision — Notes–Bibliography or Author–Date — because that choice changes how every citation in your paper is built, and it is far easier to settle it before you write than to convert a finished essay from one system to the other.
One last point worth internalising: Chicago is deliberately comprehensive because it serves disciplines that work with difficult sources — archives, manuscripts, translations, government records. You will rarely need more than a fraction of its rules for a single essay. Find the handful of source types your assignment actually uses, get those exactly right, and don't be intimidated by the size of the full manual.
A worked walkthrough: footnote to bibliography
It helps to see the whole Notes–Bibliography cycle for a single source. Suppose you are writing about Jill Lepore's history and you quote page 212 in your second paragraph. You place a superscript number at the end of the sentence, and at the bottom of the page you give the full note: 1. Jill Lepore, These Truths: A History of the United States (New York: Norton, 2018), 212. That note tells the reader everything they need — author, full title, place, publisher, year, and the precise page the quotation came from.
Later in the essay you cite Lepore again, this time page 219. Because you have already given the full details, you now use a shortened note: 4. Lepore, These Truths, 219. Surname, short title, page — nothing more. If you cite her a third time immediately after, you still use the short form; you do not need ibid., and avoiding it means your notes survive being reordered during editing.
Finally, in your Bibliography at the end of the paper, Lepore appears once, alphabetised by surname, with the page reference removed because the entry describes the whole book rather than one citation: Lepore, Jill. These Truths: A History of the United States. New York: Norton, 2018. Three appearances, three slightly different forms — full note, short note, bibliography entry — all describing the same source. Once that cycle is familiar, every Chicago footnote you write follows the same rhythm.
This is also why letting your word processor manage footnotes matters so much. As you draft and reorder paragraphs, the software renumbers every note automatically and keeps each superscript number tied to the right note. Numbering by hand all but guarantees that an inserted paragraph somewhere in the middle will throw your sequence out — and a marker will spot a footnote numbered "7" sitting between "4" and "5" instantly.
Frequently asked questions
Which Chicago system should I use?
Notes–Bibliography (footnotes) for history and the arts; Author–Date (parenthetical) for the sciences and social sciences. Your assignment brief or your discipline's convention decides.
Do you still use ibid.?
You can, but the 17th edition prefers a shortened note (author surname, short title, page) because reordered notes can leave ibid. pointing at the wrong source.
What's the difference between a footnote and a bibliography entry?
A footnote gives the source plus the specific page for one citation; the bibliography lists the whole work alphabetically, without the page reference, so a reader can see every source used.