Chicago Style Citation Guide: Complete Formatting Rules for Students

TL;DR: Chicago style offers two citation systems—Notes and Bibliography (footnotes, preferred in humanities) and Author-Date (parenthetical, used in sciences). The 17th edition discourages ibid. in favor of shortened citations. Key rules: 1-inch margins, 12pt Times New Roman, double-spaced text, hanging indents in the bibliography, and headline-style capitalization for titles. Always confirm with your professor which system they require before you start writing.

If you’re taking a history, literature, or political science course, chances are your professor has asked you to use Chicago style citations. Unlike APA or MLA, which each use a single system, Chicago style is unique: it offers two completely different citation systems within the same manual. Choosing the wrong one—or mixing them—can cost you points before your professor even reads your argument.

This guide covers everything you need to format papers, write footnotes, build bibliographies, and cite sources correctly in Chicago style (17th edition).

What Is Chicago Style?

The Chicago Manual of Style (CMOS), published by the University of Chicago Press, is one of the most widely used style guides in American publishing and academia. Now in its 17th edition (with an 18th edition recently released), it covers everything from grammar and punctuation to citation formatting and manuscript preparation.

What sets Chicago apart is its flexibility. It provides two distinct citation systems:

What we recommend: Unless your professor specifies otherwise, use the Notes and Bibliography system for humanities papers. It’s the more distinctive Chicago feature and what most instructors expect.

General Paper Formatting Rules

Before you write a single citation, your paper needs to meet Chicago’s formatting standards. Here’s the checklist:

Page Setup

• Margins: 1 inch (2.54 cm) on all sides
• Font: Times New Roman, 12-point (or a comparable readable typeface like Palatino)
• Spacing: Double-spaced throughout the main text
• Paragraphs: Indent the first line of each paragraph by 0.5 inches
• Alignment: Left-aligned (not justified)
• Page numbers: Top right corner, starting on the first page of text (not the title page)

Title Page

Chicago style typically requires a title page. Here’s how to format it:

1. Center all text on the page
2. Place the title about one-third of the way down the page
3. Use headline-style capitalization for the title
4. If there’s a subtitle, end the title with a colon and place the subtitle on the next line
5. Skip several lines, then add your name, course information, and date
6. Do not put a page number on the title page

Headings

Chicago style supports up to five heading levels. For most student papers, two or three levels are sufficient:

• Level 1: Centered, bold or italic, headline-style capitalization
• Level 2: Centered, plain text, headline-style capitalization
• Level 3: Left-aligned, bold or italic, headline-style capitalization

Keep heading levels consistent throughout your paper. Purdue OWL provides additional formatting guidance.

Notes and Bibliography System (Footnotes)

This is the system most students encounter in humanities courses. Here’s how it works step by step.

How Footnotes Work

When you cite a source in your text, place a superscript number at the end of the relevant sentence or clause—after any punctuation (periods, commas, quotation marks).

As historian Eric Foner argues, Reconstruction was “a revolution that failed.”¹

At the bottom of the same page, the corresponding footnote provides the full bibliographic information for that source.

Full Footnote Format (First Citation)

Book:

1. Firstname Lastname, Title of Book: Subtitle (Place of Publication: Publisher, Year), page number.

Example:

1. Michael Pollan, The Omnivore’s Dilemma: A Natural History of Four Meals (New York: Penguin, 2006), 99.

Journal Article:

2. Firstname Lastname, “Title of Article,” Journal Title volume number, no. issue number (Year): page number.

Example:

2. Joshua I. Weinstein, “The Market in Plato’s Republic,” Classical Philology 104, no. 3 (2009): 315.

Website:

3. Firstname Lastname, “Title of Page,” Website Name, publication date, URL.

Example:

3. Katie Bouman, “How to Take a Picture of a Black Hole,” The MIT Press Reader, March 14, 2019, thereader.mitpress.mit.edu/how-to-take-a-picture-of-a-black-hole/.

Shortened Footnote Format (Subsequent Citations)

The 17th edition discourages the use of ibid. and instead recommends shortened citations for any source you’ve already cited in full.

Format:

Lastname, Shortened Title, page number.

Example:

4. Pollan, Omnivore’s Dilemma, 125.

Key rules:

• Use the shortened form for every subsequent citation—not just the one immediately following
• If the title is four words or fewer, use the full title
• If the title is longer, shorten it to the first significant words (omit “a,” “an,” “the”)
• Always include the page number for direct quotes

What About Ibid.?

Ibid. (from the Latin ibidem, meaning “in the same place”) was traditionally used when citing the same source as the immediately preceding footnote. The 17th edition discourages this practice in favor of shortened citations, which are clearer and less prone to confusion.

If your professor specifically requires ibid.:

• Same source, same page: Ibid.
• Same source, different page: Ibid., page number.

But our recommendation: use shortened citations unless told otherwise. See the Chicago Manual of Style’s official FAQ for their reasoning.

Author-Date System

The Author-Date system works more like APA style. Instead of footnotes, you place citations directly in the text.

In-Text Citation Format

(Author Lastname Year, page number)

Examples:

• One author: (Pollan 2006, 99)
• Two authors: (Ward and Burns 2007, 45)
• Three or more authors: (Snyder et al. 2025)

The corresponding reference list entry places the publication date immediately after the author’s name:

Pollan, Michael. 2006. The Omnivore’s Dilemma: A Natural History of Four Meals. New York: Penguin.

Notice the date position: in Author-Date, the year follows the author. In Notes and Bibliography, the year appears near the end of the citation. This is the primary structural difference between the two systems.

Bibliography Formatting

Whether you use Notes and Bibliography or Author-Date, your paper needs a bibliography (or reference list) at the end.

General Rules

• Title: Center “Bibliography” at the top of a new page
• Order: Alphabetize by the first author’s last name
• Spacing: Single-space within each entry; leave a blank line between entries
• Indent: Use a hanging indent (first line flush left, subsequent lines indented 0.5 inches)
• Author names: Invert the first author’s name (Lastname, Firstname). Subsequent authors remain in normal order (Firstname Lastname).

Book Examples

One author:

Pollan, Michael. The Omnivore’s Dilemma: A Natural History of Four Meals. New York: Penguin, 2006.

Two authors:

Ward, Geoffrey C., and Ken Burns. The War: An Intimate History, 1941–1945. New York: Knopf, 2007.

Chapter in an edited book:

La Barbera, MariaCaterina. “Intersectional-Gender and the Locationality of Women ‘in Transit’.” In Feminism and Migration: Cross-Cultural Engagements, edited by Glenda Tibe Bonifacio, 17–31. Amsterdam: Springer, 2012.

Journal Article Examples

Print journal:

Weinstein, Joshua I. “The Market in Plato’s Republic.” Classical Philology 104, no. 3 (2009): 315–20.

Online journal with DOI:

Snyder, Carl D., et al. “Extant Life Detection Using Label-Free Video Microscopy.” PLOS ONE 20, no. 3 (2025): e0318239. https://doi.org/10.1371/journal.pone.0318239.

Website Examples

With author and date:

Bouman, Katie. “How to Take a Picture of a Black Hole.” The MIT Press Reader, March 14, 2019. thereader.mitpress.mit.edu/how-to-take-a-picture-of-a-black-hole/.

With organization as author (no date):

Chicago Manual of Style. “Notes and Bibliography: Sample Citations.” Accessed March 31, 2026. chicagomanualofstyle.org/tools_citationguide/citation-guide-1.html.

Citing Special Source Types

YouTube Videos

Firstname Lastname (or channel name), “Title of Video,” YouTube video, duration, publication date, URL.

Example:

USC Libraries. “Chicago Style Notes & Bibliography,” YouTube video, 3:07, April 15, 2021, https://www.youtube.com/watch?v=KvYhMwhxDxY.

Interviews

Published interview (in a magazine, newspaper, or journal): Cite it like a periodical article.

Unpublished/personal interview: Cite only in a footnote, not in the bibliography:

1. Jane Smith, interview by author, March 15, 2026.

Personal Communications

Emails, text messages, and private social media messages are cited only in footnotes, not in the bibliography:

2. John Doe, email message to author, February 20, 2026.

Common Chicago Style Mistakes (And How to Avoid Them)

Based on feedback from university writing centers across the country, here are the most frequent errors students make:

1. Mixing the Two Systems

Mistake: Using footnotes in some paragraphs and parenthetical citations in others.
Fix: Pick one system (Notes and Bibliography or Author-Date) and use it consistently throughout the entire paper.

2. Incorrect Footnote Number Placement

Mistake: Placing the superscript number before the period or comma.
Fix: The number goes after punctuation. Correct: “This is a quote.”¹ Incorrect: “This is a quote”¹.

3. Forgetting Shortened Citations

Mistake: Repeating the full citation every time you reference the same source.
Fix: After the first full citation, use the shortened form: Lastname, Shortened Title, page.

4. Missing Page Numbers for Direct Quotes

Mistake: Quoting a source without including the page number.
Fix: Every direct quote must include a page number. Paraphrased material should include one when it helps the reader locate the source.

5. Incorrect Bibliography Indentation

Mistake: Using first-line indents (like paragraphs) instead of hanging indents.
Fix: Bibliography entries use hanging indents—the first line is flush left, and all subsequent lines are indented 0.5 inches. Most word processors have a hanging indent option in paragraph settings.

6. Misusing Ibid.

Mistake: Using ibid. for non-consecutive citations or when other sources intervene.
Fix: The 17th edition discourages ibid. altogether. Use shortened citations instead.

7. Inconsistent Author Name Formatting

Mistake: Inverting author names in footnotes (they should be in normal order: Firstname Lastname).
Fix: In footnotes, author names are not inverted. In the bibliography, the first author’s name is inverted (Lastname, Firstname).

Quick Reference: Notes vs. Bibliography vs. Author-Date

When to Choose Each System

Use Notes and Bibliography when:

• Writing in history, literature, philosophy, or the arts
• Your paper has many different source types (archives, primary sources, unusual materials)
• You want to add explanatory content notes alongside your citations
• Your professor doesn’t specify a preference (this is the default Chicago system)

Use Author-Date when:

• Writing in the physical, natural, or social sciences
• Your field prioritizes the recency of sources
• You’re revising a paper frequently and need to easily add/remove sources
• Your professor or journal specifically requests it

What we recommend: When in doubt, ask your professor. A quick email clarifying which system they expect will save you hours of reformatting.

Summary and Next Steps

Chicago style may seem complex at first, but it boils down to a few core principles:

1. Choose one system—Notes and Bibliography or Author-Date—and stick with it
2. First citation = full details; subsequent citations = shortened form
3. Bibliography entries use hanging indents and inverted first-author names
4. Footnote numbers go after punctuation
5. *The 17th edition discourages ibid.—use shortened citations instead*

For official guidance, always refer to The Chicago Manual of Style Online or your university library’s citation guide. Many universities, including Purdue OWL, offer free Chicago style resources with additional examples.

Need help applying Chicago style to your specific paper? Contact our academic writing team for personalized guidance, or place an order for a custom-written paper formatted to your professor’s exact specifications.

Related Guides

• APA vs MLA vs Chicago: Full Comparison with Tables & Examples
• Annotated Bibliography Templates: APA/MLA/Chicago Examples
• How to Cite AI Tools in Academic Papers
• Assignment Prompt Decoding: How to Analyze Any Essay Question