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Chicago style citation: two systems, not one

By Alberto Gulotta · Updated 3 September 2026 · 10 min read

The first thing to know about chicago style citation is that there is no single Chicago style of citing. The Chicago Manual of Style publishes two systems, and they look nothing alike. Picking the one your department does not use is the error that costs marks, and no generator will catch it for you.

1. Find out which of the two systems you are being marked against. Not which one you prefer: the Manual itself says “students should check with their instructor before deciding which system to use.”
2. For notes-bibliography, put a note at every use of a source. Purdue’s summary of the rule: “include a note (endnote or footnote) each time you use a source, whether through a direct quote, paraphrase, or summary.”
3. Write the first note in full, and every later one short. Full: author’s name in normal order, title, publication details in brackets, page. Short: surname, shortened title, page.
4. Build the bibliography from the same sources, alphabetically. The name turns round, the brackets go, the page number goes, the page range of an article arrives.
5. Check the one rule that dates a citation. The Manual’s guide now states that “a place of publication is no longer required in book citations”: a city before the publisher marks the entry as belonging to an earlier edition of the style.

So the honest first step is not how to format the entry but which of the two systems you are being marked against. A history essay and a psychology paper can both be in Chicago and share almost nothing on the page.

One rule changed, and it is the one that dates a citation. Alongside its book examples the Manual’s own guide now carries the note that “a place of publication is no longer required in book citations”, pointing at CMOS 14.30. Anyone taught Chicago a few years ago learned to put the city before the publisher, and a marker who has read the current edition sees the older shape immediately. It is not wrong in the sense of being unreadable; it is simply the previous edition, which is exactly the impression a citation is supposed not to give.

The second thing the guide shows, and generators rarely do, is that a note is not written the same way twice. The sample notes give “full citations followed by shortened citations for the same sources” — the first mention carries everything, and every mention after it is cut down. A paper where every footnote is the full entry is a paper written by a tool that only knows one form, and it reads that way. Whichever system you are in, the sample pages are the place to check the shape: the Manual points beyond them to chapters 13 and 14 for the cases the samples do not cover.

If you genuinely do not know which one you are in, the Manual gives a reason rather than a coin toss. It describes notes and bibliography as “Chicago’s oldest and most flexible”, able to “accommodate a wide variety of sources, including unusual ones that don’t fit neatly into the author-date system”, and says that “for this reason, it is preferred by many working in the humanities, including literature, history, and the arts.” Author-date does the opposite job: the source is named briefly in the text, in parentheses, by surname and year, and each of those matches an entry in a reference list. So the question is not really which looks better. It is whether your sources are the kind that fit a form — and whether your field expects the reader to glance down at a footnote or across at a surname and a year.

Both systems are set out in the manual’s free Citation Quick Guide, which reflects the 18th edition. Chicago itself points beyond that guide: “For a more comprehensive overview of Chicago’s two systems of source citation, see chapter 13 of The Chicago Manual of Style. For many more examples organized by type of source, consult chapter 14.” Those chapters are in the manual, which is not free — the same gate that sits in front of MLA’s handbook.

The searches around this one show the same two-systems confusion. Chicago citation and chicago style format are people who have not yet been told there is a choice. Footnote citation is somebody already inside the first system, wanting the mechanics. Chicago manual of style is often someone looking for the book itself. And turabian is the student adaptation of the same manual, which is a guide of its own below.

One more thing worth saying before the guides, because it explains why this subject feels harder than it is. Almost nobody meets Chicago by choosing it. It arrives in a course handbook, usually as a single line, sometimes without naming which of the two systems is meant, and often alongside a sample essay that was formatted under an earlier edition. So the reader arriving here is rarely trying to learn a style — they are trying to match something they have been shown, without being able to see the rule behind it. Every guide below is written for that person: it shows the form first, says where the form comes from, and marks clearly the point at which the free guide stops and the book begins.

Not covered here. It will not tell you which system to use. Your department does that, and any page that answers it for you is guessing about your course.

It will not quote a rule from an edition it has not read. The Quick Guide is free and current; much of what circulates online is a paraphrase of an older edition, and the difference is not always visible.

And it will not rank the citation tools yet. That needs the awkward sources — an archive box, a podcast, a translated work — put through each of them in both systems, with the mistakes published. What holds instead is simple: every sample on this page is Chicago’s own, from the free Citation Quick Guide.