Chicago Citation Guide

Two Chicago Systems Explained

Chicago style offers two distinct citation systems. Choose the one appropriate for your discipline or as specified by your instructor:

Notes-Bibliography (NB) System

Used primarily in the humanities (history, literature, arts). This system uses:

• Footnotes or endnotes -- numbered superscript markers in the text link to notes at the bottom of the page (footnotes) or the end of the paper (endnotes)
• Bibliography -- a complete list of all sources consulted, at the end of the paper

Author-Date (AD) System

Used primarily in the sciences and social sciences. This system uses:

• In-text citations -- parenthetical references with author's last name and year: (Smith 2023, 45)
• Reference list -- a list of all sources cited, at the end of the paper

The Author-Date system is similar to APA in structure, while the Notes-Bibliography system is unique to Chicago and offers more flexibility for providing commentary in notes.

Notes-Bibliography: Footnotes and Endnotes

In the NB system, insert a superscript number at the point of citation, then provide the full reference in a note.

First Note (Full Citation)

The first time you cite a source, provide the full reference:

Subsequent Notes (Shortened)

For subsequent citations of the same source, use a shortened form:

Ibid.

When citing the same source as the immediately preceding note, you may use "Ibid." (from Latin ibidem, meaning "in the same place"):

Note: Some instructors discourage "Ibid." in favor of shortened notes. Check your style requirements.

Bibliography and Reference List Entries

Here are examples for common source types in both Chicago systems:

Book

NB Bibliography:

AD Reference:

Journal Article

NB Bibliography:

Website

NB Bibliography:

Chicago Formatting Rules

General formatting guidelines for Chicago-style papers:

Paper Format

• Use a 12-point font (Times New Roman or similar serif font)
• Double-space the body text
• Set 1-inch margins on all sides
• Include page numbers (usually top right or bottom center)
• Include a title page with the title, your name, course information, and date

Footnote/Endnote Formatting

• Use a smaller font size for footnotes (usually 10-point)
• Single-space within each note, double-space between notes
• Indent the first line of each note
• Number notes consecutively throughout the paper

Bibliography Formatting

• Start on a new page with "Bibliography" centered at the top
• Alphabetize by author's last name
• Use hanging indentation
• Single-space within entries, double-space between entries (or double-space throughout)
• Note: Bibliography entries invert the first author's name (Last, First) while footnote entries do not (First Last)

When to Use Chicago Style

Chicago style is the preferred format in several academic and professional contexts:

• History: The Notes-Bibliography system is the standard in historical writing, as it allows for detailed commentary and primary source discussion in notes
• Art History and Music: Fine arts disciplines commonly use Chicago NB for its flexibility
• Publishing: Many book publishers and literary magazines use Chicago as their house style
• Business and Economics: Some business schools prefer the Author-Date system
• Theology and Philosophy: These disciplines often use the NB system

Chicago's greatest strength is its comprehensiveness. The full manual covers virtually every possible citation scenario, making it the go-to reference for professional editors and publishers.

If you are unsure whether to use NB or Author-Date, ask your instructor. In general, humanities courses use NB, while social science and science courses use Author-Date.