Chicago referencing is widely used in history, the arts and some social sciences, and it is unusual in offering two different systems. This UK guide explains both, shows you how footnotes and author–date citations work, gives clear examples for common sources, and points out the mistakes that most often cost marks.
The Short Answer
Chicago referencing offers two systems, and your first job is to find out which one your department wants. The notes–bibliography system puts a superscript number in your sentence, the full details in a footnote, and every source again in an alphabetical bibliography — the usual choice in history and the arts. The author–date system puts a short bracket in your sentence, such as (Smith 2024, 15), and gives the full details in a reference list. Both use the same underlying information; what changes is the order of the elements and the punctuation between them. Mixing the two in one submission is the single most costly Chicago error.The Two Chicago Systems Explained
Chicago style comes in two forms. The notes-bibliography system uses numbered footnotes or endnotes plus a bibliography, and is favoured in history and the humanities. The author-date system uses in-text citations with a reference list, much like Harvard, and is common in the sciences and social sciences. Your department will specify which to use, so check your handbook before you start — never mix the two in one piece of work.
Chicago Notes-Bibliography: Footnotes and Bibliography
In the notes system, a superscript number in your text points to a footnote giving full source details the first time, and a shortened form thereafter. A first footnote for a book reads: Author First Last, Title (Place: Publisher, Year), page. The matching bibliography entry inverts the author’s name and ends with a full stop rather than page-specific detail: Last, First. Title. Place: Publisher, Year. Footnotes use commas; bibliography entries use full stops.
Chicago Author-Date: In-Text and Reference List
The author-date system places the author and year in brackets in your text, for example (Smith 2024, 15), with the page number after a comma. The reference-list entry reads: Last, First. Year. Title. Place: Publisher. This system is quicker to read and is preferred where you cite many sources, which is why the sciences tend to favour it.
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Chicago Reference Examples
Here are quick author-date reference-list templates for the sources students cite most. Book: Last, First. Year. Title. Place: Publisher. Journal article: Last, First. Year. “Article Title.” Journal Name Volume (Issue): pages. Website: Last, First. Year. “Page Title.” Site Name. Month Day, Year. URL. Adjust the punctuation if your department uses the notes-bibliography system instead.
Common Chicago Referencing Mistakes
The usual errors are mixing the two systems, using commas where full stops belong (and vice versa), forgetting to shorten repeated footnotes, and omitting page numbers in footnote citations. Students also frequently misplace the year — remember it sits differently in each system. Keeping a style guide open as you write, and being ruthlessly consistent, is the simplest way to avoid losing marks on presentation.
Shortened Notes and ibid. in the Notes System
Only the first note for a source gives everything. After that you use a shortened note containing three elements: the author’s surname, a shortened form of the title (usually no more than four key words), and the page number — for example Smith, Victorian Readers, 44. Note that a Chicago short note uses commas and no p. before the page number, which is one of the details that separates it from MHRA.
Recent editions of the Chicago manual prefer shortened notes to ibid. even for consecutive citations, because short notes remain correct when you move a paragraph and are easier for a reader to follow. If your department still allows ibid., restrict it to notes that sit immediately after the source they refer to, and never let one straddle a page break.
Where a single note supports several sources, separate them with semicolons inside one note rather than stacking numbers in your text. And where you want to comment as well as cite — noting a disputed date, or an edition you rejected — the notes system gives you room to do it, which is precisely why humanities departments favour it. The related conventions in MHRA referencing are worth comparing if you have used footnotes before.
Quotations, Block Quotes and Punctuation
Short quotations run on inside your own sentence, enclosed in quotation marks, with the note number after the closing punctuation. Chicago is an American style and its published examples use double quotation marks, reserving single marks for a quotation inside a quotation. Many UK departments ask for the reverse; follow your handbook and, above all, be consistent throughout.
Longer quotations are set as block quotations: indented, without quotation marks, and introduced by a colon or by your own lead-in sentence. As a rule of thumb, prose running to roughly a hundred words or about eight lines is better set as a block, though your department may set its own threshold. Because the indentation already marks the passage as quoted, adding quotation marks as well is an error.
Two further conventions matter. Use three spaced full stops for an omission inside a quotation, and square brackets for anything you insert, including a capital letter changed to fit your sentence. Keep the original spelling — including American spellings in an American source — and use [sic] only where a reader might otherwise think the error is yours.
Bibliography and Reference List Formatting
Both Chicago systems end with an alphabetical list, but the two lists look different. A notes–bibliography entry runs Surname, First. Title. Place: Publisher, Year. — elements separated by full stops. An author–date reference-list entry moves the year forward: Surname, First. Year. Title. Place: Publisher. That single change is what makes the in-text bracket work, because the reader looks for the author and year together.
Set the whole list with a hanging indent so that surnames sit flush left and continuation lines are indented; in Word this is a paragraph setting rather than a series of manual tabs. Alphabetise by surname, letter by letter, and where an author has several works, order them by title in the notes system and by year in the author–date system.
Chicago also has a neat convention for repeated authors in a bibliography: replace the name in second and subsequent entries with a three-em dash followed by a full stop. It is optional, and some departments prefer the name repeated in full, so check before you use it. Whichever you choose, apply it to every author with more than one entry rather than to some and not others.
Multiple Authors, Editors and Translators
Chicago handles collaborators through a small number of predictable patterns. In a bibliography, invert only the first author’s name and leave the rest in natural order. Where a work has several authors, list them all up to ten; beyond that, give the first seven followed by et al. In notes and author–date brackets, use et al. as soon as there are four or more authors, keeping the first author’s surname.
Editors and translators are introduced by role. Use edited by and translated by in full inside a bibliography entry, and the abbreviations ed. and trans. in notes. Where an editor stands in place of an author — an edited collection cited as a whole — the name comes first followed by ed. or eds. A chapter in that collection is cited under the chapter author’s name, with the editor named after the book title.
Corporate authors follow the same logic: the organisation takes the author slot, spelled out in full the first time. Where a source genuinely has no author, begin with the title and alphabetise under its first significant word rather than inventing an Anonymous entry. Our guide to referencing a book works through these variations with worked examples.
Online Sources, DOIs and Access Dates
Chicago treats digital location as the last element of an entry, and it has a clear order of preference: a DOI if one exists, then a stable or publisher URL, then a database name. A DOI is presented as a resolvable address rather than a bare string, and it is preferable to a database link because it will still work when your reader is off campus.
Access dates are not required for most published online sources that carry a publication or revision date. Add one where the material has no date at all, where the content is likely to change, or where your department asks for it as a matter of course. When you do include it, place it before the URL in a note and follow the same order in the bibliography.
For sources that exist only online, record what the page itself gives you: the organisation as author where no person is named, the page heading as title, and the site name as publisher. Fixed-page documents should be cited by their printed page numbers rather than by position in a file, a point covered in our guide to referencing a PDF, while pages that change over time are handled in our guide to referencing a website.
How Chicago Compares With Harvard, APA and MHRA
Chicago author–date and Harvard look almost identical at a glance, and the differences are all in punctuation: Chicago separates author and year with a space rather than a comma, and uses a comma before the page number without p. APA is closer again but adds an ampersand between the final two authors and demands sentence-style capitalisation for titles, where Chicago uses headline capitalisation.
Chicago notes–bibliography sits alongside MHRA as the other major footnote system. Both put full details in a first note and use short forms thereafter, but MHRA wraps publication details in brackets, uses p. and pp., and prefers single quotation marks, none of which Chicago does. Because the two look similar, they are easy to blend by accident, and blended referencing is usually penalised more heavily than a consistent style applied imperfectly.
The practical takeaway is to identify your required style before you write a word, then use one source of truth for every entry. If you have already drafted in another style, convert systematically — all books, then all chapters, then all articles — rather than entry by entry, which is where inconsistencies survive.
A Pre-Submission Chicago Checklist
Begin by confirming that you have used one system throughout. Search your document for a bracketed author and year; if you find any in a notes-based piece, you have drifted between systems. Then check that every first note is complete and every later note is shortened in the same way.
Next, read the bibliography or reference list on its own. Every surname should be inverted, the order should be alphabetical, the indentation should hang, and the year should be in the right place for your system. Confirm that everything cited appears in the list, and that a notes–bibliography list has no page numbers except for chapters and articles with a defined range.
Finally, sweep for the small details markers notice: en dashes in page ranges, headline capitalisation of titles, a DOI in preference to a database link, and access dates only where they are genuinely needed. Referencing is the one part of an assignment that can be checked for accuracy in seconds, so a clean list earns credibility before your argument is read.
Frequently Asked Questions
Which Chicago system should I use?
It depends on your subject. History and the humanities usually use notes-bibliography, while the sciences and social sciences often use author-date. Always confirm with your module handbook or tutor.
Is Chicago style the same as Turabian?
They are closely related. Turabian is a student-focused version of Chicago style with minor simplifications, so if your course asks for Turabian, the principles in this guide still apply.
Do I need both footnotes and a bibliography?
In the notes-bibliography system, yes — footnotes cite sources as you go and the bibliography lists them all at the end. The author-date system uses in-text citations with a reference list instead.
Should I use ibid. in Chicago footnotes?
Current Chicago guidance prefers a shortened note over ibid., even when the same source is cited twice in a row. A short note gives the author’s surname, a shortened title and the page number, and it stays correct if you later move a paragraph. If your department still permits ibid., use it only for a note that immediately follows the source it refers to.
What is the difference between Chicago and Harvard referencing?
Chicago author–date and Harvard both place the author and year in brackets in your text, so they look very similar. The differences are in punctuation and detail: Chicago separates author and year with a space and adds the page after a comma with no p., while Harvard conventions vary between universities. Always follow your own department’s Harvard guide rather than assuming one universal version.
Do I need an access date for websites in Chicago style?
Not usually, if the page carries a publication or revision date. Chicago asks for an access date where the source has no date, where the content is likely to change, or where your department requires it. When you include one, place it just before the web address in both the note and the bibliography entry.
How many authors do I list before using et al. in Chicago?
In notes and author–date brackets, use the first author’s surname followed by et al. once there are four or more authors. In the bibliography, list every author up to ten; beyond that, give the first seven followed by et al. Editions differ slightly, so check the manual version your course specifies.
How long does a quotation need to be before it becomes a block quote?
As a rule of thumb, prose of roughly a hundred words or about eight lines is set as a block quotation: indented, with no quotation marks. Shorter quotations run on inside your own sentence with quotation marks. Departments sometimes set their own threshold, so check your handbook and then apply one rule consistently.