Complete Chicago Style Format Guide: Notes and Author-Date, 18th Edition

Chicago Style Paper Formatting Basics

Chicago Style: Two Complete Systems

Chicago offers two distinct citation systems. Pick one and use it consistently; never mix them.

1. Notes Bibliography System

Best for: History, theology, arts, humanities

How it works:

• Superscript numbers in text¹
• Full citations in footnotes (bottom of page) or endnotes (end of paper)
• Complete bibliography at the end

Why historians prefer it: Footnotes provide source details plus commentary without cluttering the main text.

2. Author Date System

Best for: Social sciences, natural sciences, when emphasizing publication dates

How it works:

• Parenthetical citations (Smith 2024, 45)
• Reference list at the end

Why scientists prefer it: Quick publication date visibility, similar to APA format.

This guide covers both systems. Jump to your required system below.

Notes and Bibliography Chicago System Specifications

1. Paper Setup

Formatting:

• Font: 12pt Times New Roman (or another readable serif font)
• Margins: 1 inch all sides
• Spacing: Double space body text, single space footnotes
• Indent: 0.5 inch first line of paragraphs
• Page numbers: Top right or bottom center

Title Page (student papers):

• Title (centered, 1/3 down page)
• Your name (centered, below title)
• Course info (centered, below name)
• Date (centered, last)

No separate title page needed for shorter papers; put the title centered at the top of the first page.

2. Footnote Format

• In text: Place superscript number after punctuation¹
• At the bottom of the page: Footnote with full citation details

First reference to source (full format):

• Book:
  1. Jennifer Thompson, Social Movements in Modern America (Chicago: University of Chicago Press, 2023), 45.
  
  
• Journal article:
  2. Michael Chen and Lisa Rodriguez, "Urban Development Patterns," Journal of Urban History 89, no. 3 (2024): 234-56.
  
  
• Website:
  3. American Historical Association, "Research Guidelines," accessed December 20, 2024, https://www.historians.org/guidelines.
  
  
• Subsequent references (shortened):
           1. Thompson, Social Movements, 67.
           2. Chen and Rodriguez, "Urban Development," 240.
  
  
• Immediately repeated source:
           1. Thompson, Social Movements, 45.
           2. Ibid., 52. Same source, different page
           3. Ibid. Same source, same page

3. Bibliography Format

Start the bibliography on a new page after the main text.

• Title: "Bibliography" centered at top.
  
  
• Entry format: Hanging indent, single spaced within entries, double spaced between entries

Alphabetize by author's last name

• Book:
  Thompson, Jennifer. Social Movements in Modern America. Chicago: University of Chicago Press, 2023.
  
  
• Journal article:
  Chen, Michael, and Lisa Rodriguez. "Urban Development Patterns." Journal of Urban History 89, no. 3 (2024): 234-56.
  
  
• Website:
  American Historical Association. "Research Guidelines." Accessed December 20, 2024. https://www.historians.org/guidelines.

Key differences from footnotes:

• Author name reversed (Last, First)
• Periods replace commas between elements
• No parentheses around publication info
• Full page range for articles

Chicago Citation Author Date System Specifications

1. Paper Setup

Same as Notes and Bibliography:

• 1 inch margins on all sides
• 12pt Times New Roman
• Double space body text
• 0.5 inch paragraph indent

No footnotes for citations? Use parenthetical references instead.

2. In Text Citation Format

• Basic citation:
  Early settlers faced numerous challenges (Martinez 2024, 112).
  
  
• Author in sentence:
  Martinez (2024, 112) documents the challenges faced by early settlers.
  
  
• Two authors:
  (Smith and Johnson 2023, 45)
  
  
• Three or more authors:
  (Rodriguez et al. 2024, 78)
  
  
• Multiple works:
  (Brown 2022; Garcia 2023; Wilson 2024)
  
  
• Page ranges:
  (Thompson 2024, 45-52)
  
  
• No page number (general reference):
  (Chen 2024)

3. Reference List Format

• Title: "References" or "Reference List" centered at top
  
  
• Entry format: Hanging indent, alphabetized by author's last name
  
  
• Book:
  Martinez, Roberto. 2024. Western Settlement Patterns. New York: Oxford University Press.
  
  
• Journal article:
  Chen, Michael, and Sarah Williams. 2024. "Migration and Identity." American Historical Review 89 (3): 456-89.
  
  
• Edited book:
  Thompson, Jennifer, ed. 2023. Essays in Modern History. Chicago: University of Chicago Press.
  
  
• Book chapter:
  Johnson, Mark. 2024. "Economic Development." In Regional Histories, edited by Lisa Chen, 123-45. Boston: Beacon Press.
  
  
• Website:
  National Archives. 2024. "Primary Source Collections." Accessed December 20, 2024. https://www.archives.gov/collections.

Chicago Citation Formats by Source Type

Books

Notes Bibliography (footnote):
Rebecca Thompson, Colonial America: A Social History (Boston: Beacon Press, 2023), 67.

Notes Bibliography (bibliography):
Thompson, Rebecca. Colonial America: A Social History. Boston: Beacon Press, 2023.

Author Date (reference):
Thompson, Rebecca. 2023. Colonial America: A Social History. Boston: Beacon Press.

Two authors:

• Note: 2. Michael Smith and Jennifer Jones, Urban Development (New York: Norton, 2024), 45.
• Bib: Smith, Michael, and Jennifer Jones. Urban Development. New York: Norton, 2024.
• Ref: Smith, Michael, and Jennifer Jones. 2024. Urban Development. New York: Norton.

Edited book:

• Note: 3. Amanda Rodriguez, ed., Historical Perspectives (Chicago: University of Chicago Press, 2023), 89.
• Bib: Rodriguez, Amanda, ed. Historical Perspectives. Chicago: University of Chicago Press, 2023.
• Ref: Rodriguez, Amanda, ed. 2023. Historical Perspectives. Chicago: University of Chicago Press.

Translated book:

• Note: 4. Michel Foucault, Discipline and Punish, trans. Alan Sheridan (New York: Vintage, 1977), 23.
• Bib: Foucault, Michel. Discipline and Punish. Translated by Alan Sheridan. New York: Vintage, 1977.

Ebook:

• Note: 5. Sarah Johnson, Digital Archives (London: Routledge, 2024), Kindle, loc. 456.
• Bib: Johnson, Sarah. Digital Archives. London: Routledge, 2024. Kindle.

Journal Articles

Notes Bibliography (footnote):
6. David Chen, "Industrialization and Society," Journal of American History 107, no. 2 (2024): 234-56.

Notes Bibliography (bibliography):
Chen, David. "Industrialization and Society." Journal of American History 107, no. 2 (2024): 234-56.

Author Date (reference):
Chen, David. 2024. "Industrialization and Society." Journal of American History 107 (2): 234-56.

Article with DOI:

• Bib: Martinez, Luis. "Economic Patterns." Historical Review 89, no. 4 (2023): 456-78. https://doi.org/10.1234/hist.2023.04.
• Ref: Martinez, Luis. 2023. "Economic Patterns." Historical Review 89 (4): 456-78. https://doi.org/10.1234/hist.2023.04.

Primary Sources

Archival material:

• Note: 7. Abraham Lincoln to Mary Todd Lincoln, April 16, 1865, Lincoln Papers, Library of Congress, Washington, DC.
• Bib: Lincoln, Abraham. Abraham Lincoln Papers. Library of Congress, Washington, DC.

Government document:

• Note: 8. U.S. Congress, Senate, Committee on Foreign Relations, Hearings on Treaty Ratification, 89th Cong., 2nd sess., 1966, S. Doc. 45, 23.
• Bib: U.S. Congress. Senate. Committee on Foreign Relations. Hearings on Treaty Ratification. 89th Cong.., 2nd sess.., 1966. S. Doc. 45.

Historical newspaper:

• Note: 9. "Treaty Signed in Paris," New York Times, June 28, 1919.
• Bib: New York Times. 1919. "Treaty Signed in Paris." June 28, 1919.

Digital Sources

Website article:

• Note: 10. Jennifer Martinez, "Digital Humanities Methods," History Today, May 15, 2024, https://www.historytoday.com/digital methods.
• Bib: Martinez, Jennifer. "Digital Humanities Methods." History Today. May 15, 2024. https://www.historytoday.com/digital methods.

Blog post:

• Note: 11. Michael Thompson, "Understanding Historical Context," The History Blog (blog), March 10, 2024, https://historyblog.com/context.
• Bib: Thompson, Michael. "Understanding Historical Context." The History Blog (blog). March 10, 2024. https://historyblog.com/context.

Online database:

• Note: 12. Census data, U.S. Census Bureau, American FactFinder, accessed November 20, 2024, https://factfinder.census.gov.

Common Chicago Style Mistakes

Mistake 1: Mixing the Two Systems

• Incorrect: Using footnotes AND parenthetical citations
• Correct: Pick one system, use it throughout the entire paper
• Fix: Choose Notes Bibliography OR Author Date. Never both.

Mistake 2: Wrong Footnote Punctuation

• Incorrect: Thompson, Jennifer, Social Movements (Chicago: University Press, 2023) 45.
• Correct: Thompson, Jennifer, Social Movements (Chicago: University Press, 2023), 45.
• Fix: Comma before page number in footnotes.

Mistake 3: Footnote Format in Bibliography

• Incorrect: Thompson, Jennifer, Social Movements (Chicago: University Press, 2023), 45.
• Correct: Thompson, Jennifer. Social Movements. Chicago: University Press, 2023.
• Fix: Bibliography uses periods, no parentheses, no page numbers for books.

Mistake 4: Wrong "Ibid." Usage

• Incorrect: Using "Ibid." when several notes separate repeated source
• Correct: Use "Ibid." only for immediately preceding note
• Fix: If any other source appears between, use the shortened form instead.

Mistake 5: Author Date Citation Punctuation

• Incorrect: (Martinez 2024: 45) Colon like ASA
• Incorrect: (Martinez, 2024, p. 45)  APA format
• Correct: (Martinez 2024, 45) Chicago Author Date
• Fix: Comma before page, no "p."

Mistake 6: Single Spacing Footnotes

• Incorrect: Double spacing footnotes like body text
• Correct: Single space within footnotes, double space between them
• Fix: Format footnotes differently from the main text.

Mistake 7: Not Reversing Author Names in Bibliography

• Incorrect: Jennifer Thompson. Social Movements.
• Correct: Thompson, Jennifer. Social Movements.
• Fix: Last name first in bibliography/reference list.

Mistake 8: Missing Access Dates for Websites

• Incorrect: No access date for online sources
• Correct: "Accessed December 20, 2024" for websites
• Fix: Include the access date, especially for sources that may change.

Chicago vs Other Styles

For a Complete overview, refer to the Citation Styles guide for details on different citation styles and their applications.

Chicago Style 18th Edition Updates

The 18th edition (2024) introduced several changes:

Digital source improvements:

• Clearer guidance for social media
• Better streaming content formats
• Updated database citation rules

Author Date enhancements:

• Simplified multiple author handling
• Clearer DOI formatting
• Better integration with online sources

Notes Bibliography refinements:

• Streamlined "Ibid." usage
• Improved archival citation formats
• Better handling of unusual sources

General updates:

• Gender neutral language guidance
• Accessibility considerations
• Modern publication format handling

Still using the 17th edition? Update to 18th: many instructors now require it.

Free Downloadable Resources

Chicago Notes and Bibliography Template
Pre formatted document with footnotes set up

Chicago Author Date Template
Pre formatted with parenthetical citation setup

Chicago Citation Quick Reference
One page guide for both systems

Footnote vs Bibliography Format
Side by side comparison chart

Chicago Format Checklist
Pre submission verification list

Master Chicago Style

Chicago style's flexibility, offering both Notes Bibliography and Author Date systems, makes it adaptable across disciplines. Choose Notes Bibliography for history and humanities, where footnote commentary adds value. Choose Author Date for sciences where publication dates matter most.

Most mistakes come from mixing the two systems or applying APA rules to Chicago. Use this guide as a reference, pick your system early, and apply it consistently throughout. For a full understanding of all citation styles, check out our citation styles guide.