Chicago Style 18th Edition Guide

Chicago Style is one of the most flexible and widely used systems for academic source documentation.

It is particularly associated with:

One of Chicago’s most important characteristics is that it provides two major documentation systems:

  1. Notes and Bibliography
  2. Author-Date

The Notes and Bibliography system uses numbered footnotes or endnotes and is commonly used in humanities-oriented research.

The Author-Date system uses parenthetical citations containing the author’s name and publication year and is commonly used in scientific and social-science contexts where Chicago is required.

The correct choice depends on the assignment, discipline, institution, publisher, journal, or instructor.

This guide explains both systems and focuses on the reasoning behind them so that you can document sources accurately rather than simply copy citation formulas.


1. What Is Chicago Style?

Chicago Style is a comprehensive academic and publishing style associated with The Chicago Manual of Style.

It covers much more than citations.

Depending on the assignment, Chicago guidance can address:

For students, however, the most visible part of Chicago Style is usually source documentation.


2. Chicago 18th Edition

The 18th edition of The Chicago Manual of Style was published in 2024.

It introduced and clarified a number of changes to source documentation.

Among the changes are:

The exact requirements should always be checked against the edition required by your institution.


3. The Two Chicago Documentation Systems

Chicago provides two primary systems.

Notes and Bibliography

This system uses:

A sentence may contain a superscript number such as:

Research practices have changed significantly in digital environments.¹