Chicago Manual of Style (17th edition) offers two citation systems: Notes-Bibliography (footnotes + bibliography, used in humanities/history) and Author-Date (in-text citations, used in sciences/social sciences). Both require precise punctuation, italics for titles, and specific formatting. This guide provides practical examples for books, journal articles, websites, and common sources you’ll encounter in academic writing.
Imagine you’re writing a history research paper. You’ve spent weeks poring over primary sources in the archives—diaries, government documents, rare books. How do you credit these diverse materials without disrupting your narrative flow? How do you help readers find exactly the same edition you consulted?
This is where Chicago Manual of Style enters the picture. Unlike APA’s in-text author-date format or MLA’s author-page system, Chicago style (specifically its Notes-Bibliography system) allows you to place detailed citations in footnotes or endnotes, keeping your text clean while providing full bibliographic information exactly where needed. For disciplines that value source provenance—history, art history, theology, some humanities—this is the gold standard.
The 17th edition of the Chicago Manual of Style remains the authoritative guide, used by major academic journals, university presses, and graduate students worldwide. Mastering Chicago citation isn’t just about avoiding plagiarism—it’s about participating in a centuries-old scholarly conversation with precision and integrity.
Key takeaway: Chicago offers flexibility. The Notes-Bibliography system (NB) suits humanities disciplines with diverse source types. The Author-Date system (AD) fits sciences and social sciences that prioritize currency and brief in-text references.
The Chicago Manual of Style 17th edition presents two distinct documentation systems. Understanding which one to use is your first—and most important—decision.
The Notes-Bibliography system is characterized by:
Who uses it? History, art history, literature (especially older texts), theology, philosophy, and some interdisciplinary humanities fields. Historians particularly value NB because it allows extensive commentary in notes without cluttering the main text.
The Author-Date system features:
Who uses it? Physical sciences, social sciences (sociology, anthropology, political science), economics, and some interdisciplinary fields. The AD system aligns with the scientific emphasis on recency and efficiency.
Important: Your department, professor, or target journal will specify which system to use. Never choose arbitrarily.
Let’s dive deep into the NB system—the one most people think of when they say “Chicago style.”
Footnote structure:
1. First Name Last Name, Title of Book (Place of Publication: Publisher, Year), Page Number.
Bibliography structure:
Last Name, First Name. Title of Book. Place of Publication: Publisher, Year.
Key differences:
In Microsoft Word:
In Google Docs:
Two authors:
Three authors:
Four or more authors:
Chicago recommends listing all authors in bibliography but using “et al.” in notes after the first author:
If no author is listed, begin the citation with the title:
Alphabetize bibliography entries by the first significant word of the title (ignore “A,” “An,” “The”).
Chicago style omits certain publishers’ common words:
Example:
Include translator’s name after title:
If the translator is the primary focus, invert their name and list at the beginning.
The Author-Date system prioritizes efficiency and currency—critical in fast-moving scientific fields.
(Author Year, Page)
Examples:
Placement: Place the citation at the end of the sentence or clause it references, before the period.
The reference list (not bibliography) alphabetizes entries by author’s last name:
Author, First Name. Year. *Title of Book*. Place of Publication: Publisher.
Author, First Name, and Second Author. Year. "Article Title." *Journal Title* Volume, no. Issue: page range. DOI.
Author, First Name. Year. "Web Page Title." *Site Name*. Last modified Month Day, Year. URL.
Key differences from NB system:
Include page numbers in Author-Date citations when:
If you’re discussing the entire work generally, page number may be omitted.
List entries chronologically (earliest first). Multiple works from same year get lowercase letters:
Smith, John. 2018a. *Title of First Book*. Place: Publisher.
Smith, John. 2018b. *Title of Second Book*. Place: Publisher.
In-text: (Smith 2018a, 23) or (Smith 2018b, 45)
One of the most frequent questions students ask: “Which citation style should I use?” Here’s the definitive breakdown.
| Discipline/Course | Recommended Style | Why |
|---|---|---|
| History, Art History, Theology | Chicago Notes-Bibliography | Accommodates diverse primary sources; footnotes preserve narrative flow |
| Literature, Languages, Cultural Studies | MLA (Modern Language Association) | Author-page format suits textual analysis; minimal publication data |
| Psychology, Sociology, Education, Nursing | APA (American Psychological Association) | Emphasizes recency (date immediately after author); aligns with social science writing |
| Engineering, Computer Science, Physical Sciences | Chicago Author-Date OR IEEE | Author-Date provides efficiency; IEEE uses numbered references |
| Business, Economics | APA OR Chicago Author-Date | APA more common; some business journals use Chicago AD |
| interdisciplinary Humanities | Chicago Notes-Bibliography | Flexibility with diverse source types |
Important exceptions:
If in doubt, consult:
| Feature | Chicago (NB) | MLA |
|---|---|---|
| In-text | Footnotes with numbers | Parenthetical (Author page) |
| Bibliography title | Bibliography | Works Cited |
| Author names | First-last in notes; last-first in bib | Last-first throughout |
| Dates | At end of entry | After author in in-text |
| Book titles | Italicized | Italicized |
| Article titles | In quotes | In quotes |
| Publishers | Place: Publisher | Publisher, Year |
| Feature | Chicago (Author-Date) | APA |
|---|---|---|
| In-text | (Author Year, page) | (Author, Year, p. xx) |
| Reference title | References | References |
| Author names | Last-first in reference | Last-first with initials |
| Dates | Immediately after author | In parentheses after author |
| Multiple authors | “et al.” for 4+ in-text; all in reference | “et al.” for 3+ in-text; up to 20 in reference |
| Book titles | Italicized, sentence case | Italicized, sentence case |
The best way to learn Chicago style is through examples. Below are the most common source types you’ll encounter, formatted for both NB and Author-Date systems.
Notes-Bibliography:
Note: 1. Mary Beard, SPQR: A History of Ancient Rome (New York: Liveright, 2015), 142.
Bibliography: Beard, Mary. SPQR: A History of Ancient Rome. New York: Liveright, 2015.
Author-Date:
Reference: Beard, Mary. 2015. SPQR: A History of Ancient Rome. New York: Liveright.
In-text: (Beard 2015, 142)
Notes-Bibliography:
Note: 1. John Smith, "The Medieval Trade Routes," in Commerce and Culture, ed. Jane Doe (London: Academic Press, 2018), 45-67.
Bibliography: Smith, John. "The Medieval Trade Routes." In Commerce and Culture, edited by Jane Doe, 45-67. London: Academic Press, 2018.
Author-Date:
Reference: Smith, John. 2018. "The Medieval Trade Routes." In Commerce and Culture, edited by Jane Doe, 45-67. London: Academic Press.
In-text: (Smith 2018, 52)
Notes-Bibliography:
Note: 1. Amanda Lee, "Cognitive Biases in Decision Making," Journal of Behavioral Economics 45, no. 3 (2021): 234-256, https://doi.org/10.1234/5678.
Bibliography: Lee, Amanda. "Cognitive Biases in Decision Making." Journal of Behavioral Economics 45, no. 3 (2021): 234-256. https://doi.org/10.1234/5678.
Author-Date:
Reference: Lee, Amanda. 2021. "Cognitive Biases in Decision Making." Journal of Behavioral Economics 45, no. 3: 234-256. https://doi.org/10.1234/5678.
In-text: (Lee 2021, 240)
Notes-Bibliography:
Note: 1. "Climate Change: Evidence and Causes," *NASA*, last modified January 5, 2023, https://climate.nasa.gov/evidence/.
Bibliography: "Climate Change: Evidence and Causes." *NASA*. Last modified January 5, 2023. https://climate.nasa.gov/evidence/.
Author-Date:
Reference: "Climate Change: Evidence and Causes." 2023. *NASA*. Last modified January 5, 2023. https://climate.nasa.gov/evidence/.
In-text: ("Climate Change" 2023)
Notes-Bibliography:
Note: 1. James Brown, "The Future of Renewable Energy," *The New York Times*, March 15, 2022, https://www.nytimes.com/2022/03/15/renewable-energy/.
Bibliography: Brown, James. "The Future of Renewable Energy." *The New York Times*, March 15, 2022. https://www.nytimes.com/2022/03/15/renewable-energy/.
Chicago NB (Bible example):
Note: 1. Bible, King James Version, Matthew 5:3-10.
First citation: Bible, King James Version, Matthew 5:3-10.
Subsequent citations: Matt. 5:3-10.
Note: Chicago discourages citing classic works in Author-Date due to uniform pagination issues.
Always try to locate the original source. If impossible:
Notes-Bibliography:
Note: 1. Original Author, *Title* (Place: Publisher, Year), page, quoted in Secondary Author, *Title* (Place: Publisher, Year), page.
Author-Date:
(Original Author Year, page, as cited in Secondary Author Year, page)
In bibliography/reference list, include ONLY the secondary source you actually consulted.
Chicago style specifies precise formatting requirements that may be enforced by your professor or journal editor.
Margins: Minimum 1-inch (2.54 cm) on all sides (top, bottom, left, right)
Font: readable, typically 12-point. Common choices:
Line spacing: Double-space the text (including block quotes). Footnotes/endnotes are usually single-spaced with a blank line between entries.
Paragraph indentation: Indent first line of each paragraph 0.5″ (1.27 cm). No extra space between paragraphs.
Page numbers: Begin on first page of text (title page may be unnumbered). Typically placed in top right corner, sometimes centered bottom. Use Arabic numerals (1, 2, 3…).
Justification: Left-aligned (ragged right edge). Do not fully justify text unless specifically instructed.
Notes-Bibliography (book/thesis):
Title of Paper
centered, about 1/3 down page
centered, on next line: Your Name
centered, on next line: Course/Instructor
centered, on next line: Date
Author-Date (journal article):
Chicago permits various heading styles. A clear hierarchy is essential:
Option 1 (Common for student papers):
Example:
## Level 1: Centered, Headline Style
## Level 2: Centered, Sentence case
### Level 3: Left-Aligned, Bold
### Level 3. Run-in heading. Bold sentence case.
Chicago discourages numbering headings in student papers unless your discipline requires it (common in technical fields).
Quotes of 100 words or more (approximately 6-8 lines) should be formatted as block quotes:
Example:
In his reflections on modernity, Bauman argues that the very structure of contemporary life has
become fluid, uncertain, and constantly shifting. This liquidity permeates not just our
economic systems but our very identities:
Modern life has become a game of seeking and winning, acquiring and consuming, and
constant upgrading. The individual's task is to remain attractive, flexible, and
ready to change direction at a moment's notice. There is no longer a stable
foundation from which to act or a predictable horizon toward which to strive.
Not only have the certainties of the past evaporated, but the very idea of certainty
has become suspect. (Bauman 2000, 34-35)
Based on analysis of thousands of student papers, here are the most frequent Chicago style errors—and how to fix them.
❌ Wrong: The study found significant results¹.
✅ Correct: The study found significant results.¹
Rule: Superscript numbers go after punctuation (period, comma), never before. If placing after a clause, place after the comma or closing parenthesis.
❌ Wrong: Multiple “Ibid.” entries in a row without checking for source changes.
✅ Correct: Use “Ibid.” only for consecutive citations of the exact same source (same page). If citing the same source but different page, use shortened note.
Chicago 17th edition discourages “Ibid.” unless absolutely necessary. Modern usage prefers shortened notes for clarity.
❌ Wrong: Using note format (First Last) in bibliography instead of reversed (Last, First).
✅ Correct: Always reverse author names in bibliography.
❌ Wrong: Beard, Mary, SPQR: A History of Ancient Rome, New York: Liveright, 2015.
✅ Correct: Beard, Mary. SPQR: A History of Ancient Rome. New York: Liveright, 2015.
Rule: Bibliographies use periods between major elements (author, title, publication info). Notes use commas.
❌ Wrong: Retrieved from https://climate.nasa.gov/evidence/
✅ Correct: https://climate.nasa.gov/evidence/
Rule: URLs should be active hyperlinks in digital papers. Do not add “Retrieved from” or “Accessed” unless your instructor requires it.
❌ Wrong: Mary Beard, SPQR: A History of Ancient Rome (New York: Liveright, 2015), 142.
✅ Correct: Mary Beard, SPQR: A History of Ancient Rome (New York: Liveright, 2015), 142.
Rule: Book titles and journal names are italicized. Article/chapter titles are in quotes, using headline-style capitalization (major words capitalized).
❌ Wrong: (Liveright, 2015)
✅ Correct: (New York: Liveright, 2015)
Always include place of publication for books unless using the Author-Date system (which sometimes omits place for well-known publishers).
❌ Wrong: First citation: 1. Mary Beard, SPQR: A History of Ancient Rome (New York: Liveright, 2015), 142.
Second citation: 2. Beard, p. 145.
✅ Correct: After first full citation, use: 2. Beard, SPQR, 145.
OR use author + shortened title consistently.
❌ Wrong: Last modified January 5, 2023, accessed January 10, 2023, https://…
✅ Correct: Last modified January 5, 2023, https://…
Rule: For stable online sources (academic journals, government sites, news articles with clear dates), access date is optional in 17th edition. Include when:
❌ Wrong: Alphabetizing by article title “A” or ignoring “St.” vs “Saint”
✅ Correct: Alphabetize by author’s last name. If no author, use first significant word of title (ignore “A,” “An,” “The”). Treat “St.” as “Saint” for alphabetization ( Saint Paul’s comes before St. Louis’s).
While learning Chicago style manually is essential, these tools can save time and reduce errors.
Zotero (Free, recommended)
Mendeley (Free)
EndNote (Paid, institutional licenses common)
Citation Machine (Free with limitations)
⚠️ Tool Caution: Always verify generated citations against the Chicago Manual or Purdue OWL. Automated tools occasionally misplace elements (especially with edited books, chapters, non-standard sources).
The Chicago Manual of Style, 17th Edition
Purdue OWL (Online Writing Lab)
Your University Writing Center
Download these pre-formatted templates to avoid layout errors:
General Paper (Notes-Bibliography):
https://owl.purdue.edu/owl/research_and_citation/chicago_manual_17th_edition/cmos_nb_sample_paper.html
General Paper (Author-Date):
https://owl.purdue.edu/owl/research_and_citation/chicago_manual_17th_edition/cmos_author_date_sample_paper.html
Chicago style doesn’t limit footnote quantity. In fact, historians often have extensive footnotes. However, for typical undergraduate papers, 20-50 footnotes across a 10-15 page paper is common. Over 1 footnote per paragraph may indicate over-citing.
Chicago Author-Date is acceptable for some social sciences and interdisciplinary fields. However, most pure sciences (biology, chemistry, physics) use:
Check your target journal’s guidelines.
Yes. Chicago NB requires both footnotes/endnotes AND a bibliography. Exceptions:
Use shortened notes after the first full citation:
First citation: 1. Mary Beard, SPQR: A History of Ancient Rome (New York: Liveright, 2015), 142.
Second in same paragraph: 2. Beard, SPQR, 145.
If citing consecutively (no other sources in between), “Ibid.” is acceptable but not required. Many Chicago style guides now discourage “Ibid.” for clarity.
For ebooks or websites without stable pagination:
For Author-Date in-text: (Smith 2020, chap. 3) or (Smith 2020)
Yes! Chicago NB is perfectly appropriate for:
Check first: Many introductory courses prefer MLA or APA because they’re simpler. Reserve Chicago for when specifically required or for advanced humanities work.
From a reader’s perspective, footnotes are more accessible (no page-flipping). Endnotes preserve page aesthetics but require more effort.
No. Citation requirements vary by discipline:
No. Use one consistent style throughout your paper (unless explicitly instructed otherwise). Mixing styles appears unprofessional and confuses readers.
Add lowercase letters after the year in Author-Date:
Reference list:
Smith, John. 2020a. *Title of First Work*. Place: Publisher.
Smith, John. 2020b. *Title of Second Work*. Place: Publisher.
In-text: (Smith 2020a) or (Smith 2020b)
This doesn’t apply to NB footnotes—just use shortened titles to differentiate.
You’ve now learned the essentials of Chicago Manual of Style citation:
Key distinctions:
What to do next:
For comprehensive citation knowledge, explore these related resources on our site:
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